Through the magic of google alerts I came to your page and I think you bring up a really valid point and it evoked some thoughts in my mind that I thought I would throw out there – maybe it’s useful. I suffered for a long time from doing too much new material and not working on the same material over and over to perfect it.
Maybe I’m someone who takes longer to grasp things than other people, but once I moved to New York I was given advice by a few people to “really work on my 7 minutes” for the sake of a tape or to have a polished audition set. I resisted it for a while, but once I started doing it, in addition to getting out of NY to perform in front of other audiences, it helped so much - and for a lot of the reasons you stated – building confidence, finding new tags, better economy of words, stronger punches – but the biggest for me – it taught me how to make the timing, rhythm and therefore delivery the joke as consistent as possible.
With that in mind, it made it a lot easier to try new material because I had honed my delivery or voice creating a more consistent act all round.
Really good point I think. Doing the same stuff over and over really does help you determine what your voice is and whether other material fits in.
That said, I still worry that it can lead to autopilot syndrome where you lose spontaneity and just turn into a drone. But I think there's a balance to be had...just a question of finding that sweet spot.
Oh, and one more thing that's nice about telling the same jokes over and over. You know how good they are. When an audience doesn't laugh at a joke that you know is funny, you can just shrug it off. Makes it easier to keep your confidence up.