He participated in Ludum Dare (ludumdare.com), as did I, it's always a blast. I think you can't be thinking of going indie without having participated at least once sucessfully in a ludum dare (either in the jam or the compo, doesn't really matter)
I agree. Ludum Dare teaches you YAGNI. I built a better screen engine during LD in a couple hours than the bloated disfunctional monster I was building for my hobby game I had spend a dozen hours on. "First make it work, then make it modular" and "Create something small that works and then iterate" are now my game design commandments that I constantly have to repeat.