Movies either work or they don't work and they're either funny or they're not and we work very hard. To achieve that kind of work is really kind of delicate stitching. ↗
The most important thing is to write material that YOU think is funny. If you don't think it's funny, but you're convinced that other people will think it is, well they won't. ↗
I wouldn't totally rule out doing Letterman or the Tonight Show if I had a set that I just happened to write that I thought was funny but was still appropriate for network censors. But I'm not going to go out of my way. ↗