There's only a few that I don't because they were either created as part of a request and I have no personal need for them, or because somebody else has released an extension after mine that does the job better or has more features.
I don't use all of mine. I've done stuff that was requests from other people and I've done stuff that I used on one style or another but dropped at some point. For me, I like trying new things all the time. Some of it becomes truly useful for my site. Others don't and get dropped during the next upgrade cycle.
I have couple that I made myself, but the coding is ugly and beiggner that is no worth of releasing, but I'm trying to learn right now so that one day I could create better ones . As for couple of other ones, there not really mine cause they were custom made for my site by coders such as Cinq.