It was bizarre to me, too. I thought most of what you mentioned was just testing his commitment. Solid commitment should mean something decent looking would come out of those efforts. The email and 4 days are probably just their instincts in action with some deliberation on latter after doing this kind of thing regularly for a long time.

I'm curious how long it takes on average for most VC's to go from good interview to acceptance.

Hustles are all about commitment, and one of the ways you can tell you're being hustled is when your side has to establish its decisionmaking ASAP while their decision process then can take however long they feel like.

That is a common pattern. I recently blew someone's alleged deal off because they needed a decision immediately. It's usually a bad sign but might be normal with VC's.