If the benefit of adding a new employee is lower than the burden within the organisation that adding them causes, it sounds a lot like a concurrency issue more

If the benefit of adding a new employee is lower than the burden within the organisation that adding them causes, it sounds a lot like a concurrency issue more than an headcount issue as such. What they're describing seems to be too many people working on the overlapping/interacting projects and relying heavily on synchronous communication (which they can't even schedule, talk about contention!) to move. If the teams were better isolated, given more autonomy and asynchronous communication between them encouraged then things would probably go a lot more smoothly. So I think it's less of a headcount issue and more of a structure issue. But I suppose it also depends on what work is available and what the integration requirements are as well, depending on what they've got this might not be possible.