If interruptions and meetings are the worst thing to break your flow then I feel like you haven't dealt with truly bad build systems where builds take multiple minutes to run on a good day.
Build times can be the most important factor if they take like 20 minutes. Which I actually have seen before, I've seen some monster C++ and Java builds in my time.
The developer experience is completely different in such an environment.
Mostly agreed, but don't discount tooling quality as a major source of flow-breakage.
There's often friction and lack of documentation about tooling. This results in much more frustrating flow-breakage IMO. This is something that we could fix but choose not to because we can't clearly articulate the loss from flow-breakage.
Staying "in the flow" is difficult, but build time is clearly not the unique or maybe even the most important factor.
Good tooling should be expected to not break the flow, but from my experience, interruptions and meetings are far worse.