Here's an excerpt of from an article entitled "The Church of Comedy" by David Dobkin - probably the best words I've read about comedy directing.
10. YOU NEVER KNOW WHAT YOU HAVE UNTIL YOU ARE DONE EDITING
When you get to the edit and watch your assembly, you will want to cry. Almost nothing works. That’s because it’s not a movie yet. It’s an assembly. And the process you go through between that moment and a finished film is where you find out what you really have: the magic you’ve captured, and the magic you’ve missed."