This whole thread is good but highlighting this b/c "make a decision & run with it" is good advice for life generally, not just academia. If you couldn't make good decisions you wouldn't have gotten this far, plus, post-decision rationalization is always there to rescue you.
5.2. ...chances are, you just need to make a decision and run with it. some of the things will fail. but at the end of the day, you have a million cool things you can work on. don't lose sleep on any of it.