I don't know whether this is in the guide anywhere, but I found out by accident how to to descend ladders very quickly, just press B and hold when you're on the ladder. You slide down very fast. There are some big ladders in this game!
I'd seen people doing this in vids, but never thought to ask anyone. Good tip. I'll also add a tip to yours - if you need to get down a ladder and there are some nasties at the bottom, toss in one of those alluring skulls to distract them.