Well, for me, not fixing minor things now means I'll definitely have to change everything later. I can't tell how good or how bad a sentence is unless the grammar and punctuation are correct. This really means I don't just change minor punctuation, I change everything now, so I won't have to do so later.
Changing things later almost always means there's a whole blasted novel that needs changing, maybe even rewritten and revised. That's more work than I want to do, and slower than I want to write.
So I change the tiny things on the page I'm writing. Then I change everything these tiny changes make me change, and then I change the big things, and then, when I'm finished, I go through and change the tiny things again.
But I see your point. I just know that, for me, there is no such thing a s a tiny change. Anything I leave undone in a sentence is a major thing because it doesn't let me see the sentence as it really is.
