According to his private secretary, Winston Churchill would invest one hour of preparation for every minute of delivery. And so for a major set piece speech in the House of Commons, running to 45 or 50 minutes, we are talking of 45 or 50 hours of preparation. While fighting Hitler at the same time.
It's interesting to see how much prep time Churchill would put into his speeches. While comedians ain't giving speeches about fighting a war, that ratio of prep time to finished product is prob worth keeping in mind.
The finished product is just the tip of the material iceberg. Way more gets buried under the surface.
I think about this sorta thing in terms of a 1/2 hour standup special (or headliner set). It's not about getting to 30 minutes worth of material. It's about getting way more — 300 minutes worth of material? — and then picking out the best (or most appropriate/thematic) half-hour of stuff from that.