Cleaning a BP gun is a sport in itself, as is casting your own roundballs. One thing I've learned about BP shooting - there are few absolutes. Some clean their guns all the time, some don't, some use lube, some don't, some use .451, some use .454 or .457. Some shooters like 777 or Pryodex - I like Goex. I clean my guns after every shooting session mostly because I've bought some older, used guns that hadn't been cleaned and the innards are in tough shape. Plus, I like tinkering with the internals.
Check out my latest purchase - it's a little complicated but not as bad as a Paterson.