Most multi-site groups arrive at the same architecture by accident. A franchise opens, it wants a web presence, so it gets a site or a subdomain of its own. Repeat that thirty or forty times over a decade and you have a network of sites under one brand, all publishing near-identical pages about the same products and chasing the same searches.
Internally it feels fair, because each location owns its own patch and answers for its own numbers. Seen from outside, though, it is one company whose sites all chase the same customers.
What search engines do with it
Google has to pick one. Faced with forty pages that describe the same product in nearly the same words, it chooses whichever seems strongest and largely ignores the rest - and "strongest" is decided by signals that are now split forty ways. Links that would have accumulated to one authoritative page are scattered, and so is the behavioural data. So a brand that should own its own category ends up sitting below competitors who consolidated years ago, and below manufacturers selling direct.
Paid has the same problem and it shows up on the invoice. Separate accounts bidding on the same keywords push each other's costs up, so the group pays more for the same clicks.
The part customers notice
The customer experience is where this starts costing money. Someone in one city searches for a product, lands on a location three hundred miles away because that page happened to rank, and then meets a delivery charge or a collection point that makes no sense for them. Most of them leave. The ones who don't have had a worse experience than they needed to, and the location that actually could have served them never saw the visit.
What consolidating buys
Worth being precise about what needs consolidating, because it's the generic demand rather than the sites themselves.
The local sites can stay exactly where they are, doing the job they're good at: serving customers a branch already has, and giving that branch something of its own to promote. What has to stop is forty of them chasing the same national search. One site carries that demand with one budget behind it, and the local sites point at it rather than compete with it.
The budget point is the one that usually lands with a finance director. Fragmented per-location spend cannot be moved to where it works, whereas a single national budget can be pushed toward whichever regions, products or seasons are performing and pulled back from those that aren't, and none of that requires the campaigns themselves to change.
Consolidation also stops the architecture working against local SEO. Location pages with genuine local substance, a managed Google Business Profile per site, and consistent name, address and phone data will hold local visibility perfectly well without each branch needing its own domain to defend.
The objection you have to answer first
Every network we've discussed this with raises the same thing, and they're right to. If a national store starts taking the searches, what does the individual location get out of it?
The answer has to be measurement, and it has to be built before you ask anyone to change anything. Each location needs to see the orders, calls and enquiries the national store produced for them - by name, in a report they trust. Without that, it reads to the branches as head office taking something away, and the politics of that will usually stall the project regardless of how good the search case is.
Which makes this an analytics and reporting project at least as much as a search one. The tracking has to identify which location fulfilled a given order and attribute it back to that location, and it has to be reliable enough to hold up when a regional manager queries a number.
Where we've done it
We've now done this twice in the same category. With Office Products Depot, 23 dealer locations each ran their own store on their own subdomain, and the answer was a national B2C store to carry the generic demand while the dealer sites stayed put and pointed at it. Generic product terms rank now that previously didn't, and dealer-level attribution means each member can still see what the national store produced for them. We ran a close variant of the same problem for Office National across 100+ locations.
If your network is structured the old way, the test is simple enough. Search for one of your main products, in a city where you have a branch, and see which of your own sites turns up - and whether that's the one that should have.
