If you're asking chances are you won't need them.
If you're coming home with sore joints and scrapped up arms and knees I should hope that that's an obvious answer enough and you do in fact want to get some padding of sorts (if only just the pads in your pb pants). The pads in most pants are not as well as regular pads, but they're designed (in many cases) to work with one another.
They don't make mistakes. They don't do random. There's always an objective, always a target.