Comment by lordnacho

Could it be that what we called flow state was actually a sort of high level thinking time afforded by doing low level routine work?

For instance I'm the old world, if you wanted to change an interface, you might have to edit 5 or 6 files to add your new function in the implementations. This is pretty routine and you won't need to concentrate that much if you're used to it, so you can spend that low-effort time thinking about the bigger picture.