Discussion: How Often Do You Use Pre-Generated Content?

 With all the work on building dungeons, I'm curious how often you use pre-generated content for your games?

For the longest time I thought there was two ways to game. Almost fully custom content - which is the way I've GMed for most of my life - and running pre-generated campaigns and adventures. A friend recently introduced me to how he runs campaigns, which is he takes a bunch of adventures, swaps around some of the NPCs, builds custom content links between them, and then strings those together for the game that he wants to run.

This is definitely not a style I could do really. I think at this point I need to customize and be able to wing so much that it'd be hard to move into those confines. My mind somewhat naturally rebels against it. With a bunch of adventures written like "Jewel of Yavin" I could possibly do it, but that adventure is less a "run these events this way" and more a "This is a heist. here are the maps, here are the players, here are some events, go nuts and have fun."

What about you? How do your games work? How much content do you customize?