My old boss in Denver said my emails were too long, so I cut them to 2 lines and now I get replies in 10 minutes
I thought being thorough was the whole point until he asked me why I write a paragraph when a yes or no would do, and honestly that one line from 4 months ago fixed the way I write everything.
Two lines isn't the magic number, it's the replying part people skip. What your boss really taught you was to put the ask up front so the other person doesn't have to dig. I've seen 5 line emails get answered fast because the question was in line one, and 2 line emails get ignored because they were vague. Short helps but clear is what gets the reply. That one line from 4 months ago probably fixed the thinking more than the typing.