Interesting that there's no step in the flowchart for an investor to exit the flow after a verbal yes. A 100% close rate may be normal for a YC company but in my experience it's not typical. You want to get a "No" as fast as possible, which I've seen happen at every stage of the pipeline, including after signed docs (although rarely).
I agree, we've never closed 100% of yeses. However, dragging it out with one of those investors, assuming they refuse to say no is worse for them imo as it creates a clear paper trail of bad behavior which hurts their reputation.
This is true, investor and for that matter 'executive' lock-in is significantly more substantial than an individual contributor, and so (rightly so) is the investment to return. It's an interesting paradox. Reputation matters.