Add up what your agencies say they sold last quarter, then compare it with the bank. The numbers are an example:
£190,000 ÷ £130,000 = 1.46. All 3 agencies look excellent, and the business is flat.
You have bought 3 marketing strategies, each aiming at a different goal, and nobody is accountable for the total.
Why it feels logical
Meta is its own world. Google works differently. Email is a specialist skill. You want people who do only that one thing.
That is right at channel level and wrong at business level. Your customer does not live in channels. They see a Meta ad on Monday, click a Google Shopping result on Wednesday, open an email on Thursday and buy on Friday. All 3 agencies claim the sale.
What it costs, 4 ways
Attribution overlap. Meta counts 7-day click and 1-day view. Google counts sales up to 30 days after a click. Email counts anyone who opened in the last 5 days. One sale can appear in all 3 reports, which is how the example above reaches 46% over.
Duplicated spend. Meta retargets website visitors. Google bids on your brand name to catch the same people. You pay twice to reach buyers who were already coming back.
Clashing messages. Meta runs a product launch. Email runs a clearance on the same products. The Google Shopping feed shows old prices. The customer sees 3 versions of your brand in a day.
No owner for MER. Ask the Meta agency why MER fell this month and they quote platform ROAS. Ask Google and they quote theirs. Email shows open rates. None of them can own total efficiency, because each only sees its own slice.
Check yours in 10 minutes
- Pull your last 3 months of agency reports.
- Add up the revenue each one claims.
- Divide by your Shopify revenue for the same months.
Above 1.2 (20% over) is a real overlap problem. Then ask who owns MER: total revenue ÷ total marketing spend. If the answer is “everyone” or “nobody”, the cost is higher than it looks.
2 setups that work
- One integrated agency. 1 team across paid social, paid search and email, on 1 strategy and 1 set of numbers. Overlap is removed by design, and budget moves against 1 MER target.
- An in-house lead above specialist agencies. A Head of Marketing or CMO owns the marketing P&L, sets the budget and holds each agency to MER instead of its own channel metric.
Asking the agencies to coordinate does not work. They have different data, different incentives and different definitions of success. Coordination has to come from 1 level above them.
Related reading
- In-house vs agency for ecommerce marketing: the structural decision behind this one
- How to allocate your ecommerce marketing budget: budget that only works when someone owns the cross-channel view
- What is blended ROAS?: the number that makes overlap visible
One set of numbers starts with one budget. Check what your margin can afford.
Our growth strategy and tracking and reporting services keep every channel on one set of numbers. If your reports disagree with Shopify, book a free call and we will find the overlap.
Quick answers
Why is using separate agencies for each channel a problem?
Each agency optimises its own channel metrics without seeing what the others do. The Meta agency targets people the Google agency already converts. The email agency does not know Meta is retargeting the same buyers. Nobody owns the journey across channels, and nobody is accountable for total marketing return.
How much money does channel fragmentation typically waste?
Agency reports often claim far more than Shopify banked, because several agencies claim the same sale. In the example above it is 46%.
What is the alternative to one agency per channel?
Either 1 integrated agency that runs your paid channels on 1 strategy and 1 measurement framework, or a strong in-house marketing lead who coordinates specialist agencies. Someone must own the cross-channel view: total MER, the customer journey and the budget split between channels.
Is it ever appropriate to use separate agencies for different channels?
Yes, when 1 channel is big enough for a dedicated team and a strong in-house lead coordinates them. Without that coordination layer, separate agencies drift apart and nobody notices until the P&L suffers.
