I could save a meaningful amount of time in Flow if the editor was a little easier to use, though it's hard for a non-UI Researcher to describe in words what you could easily see in a usability lab, but I'll try. <g/>
basically, i spend most of my time trying to get the cursor where i need it. A related problem is that I don't always know where it is until I either delete or insert dynamic content.
my guess today is that i'm successful about 50% of the time.
workarounds are getting the cursor visible at the beginning of a line then backspace up to the line where i insert, then add the deleted blank lines until the original line is where it belongs.
other issues are that delete and backspace don't behave consistently, especially when I have selected words, phrases, or lines. Usually i have to move the cursor to the left side of the selection, then backspace.
i'm not even sure whether delete and backspace work the same when either one is appropriate. i believe backspace is the most reliable way to edit.
Another usability issue is dynamic content. I have constructively criticized editing dynamic content elsewhere, but the main issue (aside from a perceived paucity of docs on dynamic content, something i will attend to personally in the next few days) is that once i create a new dynamic node unintentionally, i cannot remove the node from the list for subsequent edits. the worst case here is that some of the extraneous nodes appear in the PowerApps Run() method (and i think that happens when, for example, i have selected Ask PowerApps only to see a node that is not in my known schema).