My personal experience has been that if I pack for all reasonable scenarios ('cause Mr. (Colonel) Murphy is never far away), I have rarely had cause to use the equipment. Which breeds complacency and has me doubting the wisdom of lugging around all of this weight. Then I remember, if I don't have it, I'LL NEED IT!
Proper Planning Prevents [censored] Poor Performance - the 6 P's have never failed me.