You're right! However, it's inefficient for a developer to always be doing that much non-development work. And it is possible to get real work done during the small windows, but only certain types of real work. Occasionally you can fit in a bunch of good bug-fixes. Other times you're able to organize things into discrete small tasks up-front, and you can get a few of those things done with each small window. But, it's impossible to really achieve flow in those circumstances. The lack of flow is really the gist of my argument.