Growthcart is a full service digital marketing agency, and we still tell some prospects to hire three firms instead of us.
That sounds like a strange thing to put in writing. It is also the honest answer to the question we get asked most on first calls: should one agency run SEO, paid ads and the website, or should each go to a specialist?
The answer depends on how much you spend, who is doing the work day to day, and whether anyone on your side can referee between suppliers. It is one of the structural choices in choosing a digital marketing agency in the UK. This article sets out the trade-offs as plainly as we can, then gives a decision table by business size and a short list of warning signs that an agency has taken on more channels than it can staff.
What you gain from one agency
The real benefit of one agency is a single person who owns the whole result. When the SEO team wants a new landing page, the web developer sits two desks away. When paid search starts bidding on a term that organic already ranks for, someone notices because they see both reports.
That coordination has a cost when you split it up. A business with three suppliers becomes the project manager by default. You chase the web agency for a page, then the SEO agency for the copy, then the paid agency for the tracking, and each of them blames the other when the number does not move.
Pat East put the case for a single partner in a piece for PPC Hero that still reads well a decade on. One contact simplifies communication, one person is accountable for poor performance, and the agency becomes a wider confidant who understands how the parts of the business fit together.
There is a budget argument too. ExpertMarket's UK pricing guide, last updated in March 2025, puts the average individual service retainer at about £960 a month, with SEO around £1,000, PPC management around £1,100 and organic social around £1,200. Buy those three separately and you are paying three sets of account management overhead before any work is done. How each of those retainers is priced is its own question, set out in marketing agency pricing models.
What you lose
What you lose with one agency is depth, and the risk is that the same mid-level person ends up running every channel. East's line on this has not aged either.
"The person communicating with you cannot be an expert in every discipline." Pat East, PPC Hero
SEO and paid search look similar from the outside because both involve keywords. The daily work is different. A good paid account manager lives in bid strategies, feed quality, conversion tracking and creative testing, the day-to-day of a dedicated Google Ads agency. A good SEO lives in crawl logs, internal linking, content briefs and Search Console, the day-to-day of a specialist SEO agency. One person can know both. Very few people can be excellent at both while also handling a website rebuild.
The clearest picture of what "spread thin" looks like comes from practitioners, not agencies. In a thread on r/PPC, a specialist managing 90 accounts alone described a plan from their boss to split the load so that two people would each hold 45 accounts and divide their time between PPC and SEO. The replies were blunt. One agency owner said he would not want anyone above 40 to 50 small accounts, and only if they had no SEO and no client calls. Another said 45 was too many for one person and suggested finding a new job.
The same thread has people who manage five to eight accounts each and say that is the ceiling for doing the work properly. Those two groups charge very different fees and deliver very different results. When you buy a bundle, you often do not know which group your account has landed with.
Why clients are splitting agencies anyway
Clients are moving work between agencies because many are unhappy with what the bundle delivered. Gartner's 2025 CMO Spend Survey, which polled 402 marketing leaders in North America, the UK and Europe, found marketing budgets flat at 7.7% of company revenue and 39% of CMOs planning to cut agency budgets further. Decision Marketing's coverage of the same survey notes that agency spend had fallen to 20.7% of marketing budgets and was still dropping year on year.
Those are big-company numbers. The pattern at the smaller end is the same, and it shows up in the forums where business owners ask for recommendations. In a January 2026 thread on r/digital_marketing, a D2C founder asked for an agency that could deliver traffic, leads and revenue. The most useful reply did not name an agency. It said, "You don't always have to pick one agency for everything," and asked which channels actually mattered to the business.
Another commenter in the same thread argued that agencies lean on a junior hire doing a couple of hours a week on each account, and that the founder would do better hiring in-house or using contractors for specific tasks. That is the freelancer versus agency trade-off in miniature. A third said they had seen more businesses hurt by hiring the wrong agency than by having no agency at all. Those are three strangers, and each had the same instinct: buy the channel you need from someone who does that channel well.
The large-advertiser data points the same way. A 2022 WFA and Observatory International study of 32 major advertisers found that 60% wanted to cut the number of agencies on their roster, while only 25% were very or extremely satisfied with their current set-up. Consolidation and dissatisfaction were happening at the same time. Fewer suppliers did not mean happier clients.
A decision table by business size and spend
The right model follows your monthly spend and whether you have someone in-house who can manage suppliers. The table below is how we talk prospects through it. The spend figures are the agency fees plus media, and the bands are rough.
| Situation | Typical monthly budget (fees plus media) | Our recommendation | Why |
|---|---|---|---|
| Local or single-site business, no marketer in-house | Under £3,000 | One agency, two channels at most | You cannot afford three retainers, and nobody on your side has time to coordinate them. Pick the two channels that matter and do those well. |
| Growing SME, one marketing person in-house | £3,000 to £10,000 | One lead agency, with the right to bring in a specialist for one channel | The lead agency owns the result. If paid spend passes about £5,000 a month, ask who is in the account daily and consider a specialist for that channel alone. |
| Established business, small marketing team | £10,000 to £30,000 | Lead agency for strategy and web, specialist for the biggest channel | At this spend a 1% improvement in paid efficiency pays for a specialist. Keep one agency accountable for the plan so the specialist is not working in isolation. |
| Larger business with a marketing director | £30,000 and up | Specialists per channel, coordinated in-house | You have the budget to buy depth and the people to referee. A full service agency at this level is often reselling specialists anyway. |
| Any size, during a website rebuild | Varies | Web agency plus whoever runs SEO, in the same room | Migrations lose rankings when the developer and the SEO never speak. If they are at different firms, you must force the meeting. |
Two notes on this. First, the £5,000 paid media threshold is ours, not a published benchmark. It is the point at which we have seen generalist management start to cost more in wasted spend than a specialist's fee. Second, "one agency" in the first row only works if that agency actually has a specialist for each channel it sells. Which brings us to the warning signs.
Four signs a full service agency is spreading too thin
The signs are easy to check on a sales call, before you sign. Ask the questions directly, alongside the broader questions to ask a marketing agency. An agency that is staffed properly will not mind.
The same person runs every channel on your account. Ask who will be in your Google Ads account on a Tuesday, who writes the SEO briefs, and who commits code to the website. If the same name comes back three times, you are buying a generalist at a specialist's price.
There is no specialist on the call. A well-run agency brings the person who will do the work to the pitch, or at least to the kick-off. If you only ever meet an account manager, the people doing the work may be the 45-accounts-each team from that r/PPC thread.
The reporting blends channels. "Website traffic is up" tells you nothing about whether SEO or paid did it, or whether one is cannibalising the other. Ask for a monthly breakdown that shows cost, leads and revenue per channel. If the agency resists, it is because the blended number hides something.
There is no channel they would turn down. Ask what they do not do. We do not run TV or out-of-home, and we say so. An agency that says yes to every channel, including ones it has never run for a client in your sector, is selling a logo wall. Hawke Media's piece on the same question calls this the "buffet" problem: a list of disconnected services that only looks integrated on the proposal.
How to run a split without becoming the project manager
A split works when one party is named as the lead and the others know it. The failure mode is three agencies, three logins, three dashboards, and a business owner stitching it together on a Friday afternoon. Hawke Media's name for that outcome is "vendor soup", and it is the right name.
The fix is a short written agreement before anyone starts. Who owns the conversion tracking? Who signs off on a landing page change? Which agency gets the call when a lead drop could be either a tracking fault or a bid change? Give one firm the job of answering those questions, and put it in their scope. It does not matter much which one, as long as it is written down.
Shared access helps. Every supplier should be in the same Google Analytics property, the same Search Console, and the same ad accounts, with access logged. A specialist who cannot see what the other agency changed last week will guess, and the guess will be wrong.
Finally, keep the reporting on one page. Ask each agency for the same three numbers in the same format: cost, leads, and cost per lead, for their channel. Then you can compare without anyone's dashboard flattering them.
Where that leaves us
We are a full service agency, and our view is that the model only works when every channel sold has a named specialist behind it. If a prospect's paid spend is the whole business and they need someone in the account every day, we say so, and we have pointed people to pure paid shops when that was the better fit. If their website needs rebuilding and their SEO lives with another firm, we ask to meet that firm before we start.
The decision rule is simple to state. Buy coordination from one agency when your budget is small and nobody in-house can coordinate. Buy depth from specialists when a single channel is big enough that a few percentage points of efficiency pay for the extra retainer. In between, hire one lead and keep the right to add a specialist, and check the four signs before you sign.
If you want a frank view on whether our paid media or SEO team should run your channel, or whether a specialist would serve you better, talk to us and we will tell you either way.