Mine is mostly full and it's not stuff I've saved but stuff software has stored there without asking me. It's quite hard to figure what's going on. I once got a message from Chrome saying it couldn't go on because it had stored like 200gb for websites, would I like to delete it all, and I said yes and noticed no difference.

It's annoying because I'd rather store say family photos than have it full of random junk that means nothing to me. Dunno the answer - better os control? Partition the drive?