When your organisation has outgrown informal coordination
There is a size at which informal coordination works well. In a team of five or six people who sit near each other and share context, a lot can be handled by conversation. Somewhere between fifteen and thirty people, that stops being true. The conversations that used to carry the organisation start dropping things. This is not a failure of the people involved. It is a structural problem, and it has structural solutions.
The signs that something has changed
The most common early sign is that the same question gets asked by multiple people in different parts of the organisation, and the answers they get are different. This happens because the information that used to live in shared context now lives in individual heads, and those heads are no longer in constant contact.
A second sign is that decisions that used to be made quickly now take longer, without any obvious reason. The organisation has not become less capable. It has become larger than its coordination mechanisms can handle.
What not to do
The instinctive response to coordination problems is often to add meetings. More touchpoints, more check-ins, more all-hands sessions. This sometimes helps in the short term, but it does not address the underlying problem, and it adds to the meeting load that is already slowing people down.
The other common response is to hire a coordinator or project manager whose job is to hold the information that used to be held informally. This can work, but it creates a single point of failure and does not build the structural capacity the organisation actually needs.
Simple structures that scale
The most durable coordination mechanisms are written ones. A short weekly update from each team lead, in a standard format, distributed to the whole organisation. A decision log that records what was decided, by whom, and when. A single place where current priorities are listed and kept up to date.
None of these require new software. They require agreement on a format and the discipline to maintain it. The format matters more than the tool. A well-designed one-page template that everyone uses is more useful than a sophisticated project management system that nobody fills in consistently.
If your team has grown past twenty people in the last two years and coordination feels harder than it used to, that is worth looking at directly rather than waiting for it to resolve itself.