The big rounds are tempting. But find that they equal more work than the more manageable stuff. I mostly process wood alone and I find my max for oak is about 16 inch diameter for a 20 inch long log. Past that, I’m asking to mess up my back. There’s always noodling or splitting the bigger stuff into smaller pieces but that’s more work involved. It is magical, though, how the big rounds produce seemingly endless splits. It’s like printing money.