Do you really use the Encumberance system?

So far I haven't, because keeping track of everything's weight is a pain, and my games are running slowly enough as it is... But it's been pointed out to me that those, as well as the jumping rules, are under-utilised ways to keep the game balanced, and have more utility for martial classes. It would make sense that those classes can use their skills out of combat, just like spellcasters can use theirs.

What do you think about it? Did you find a way to make inventories easier to manage?