I think you get a lot more long term generational growth if you can wait and take real big ones.
If I was using a splitter I would like anything that would give me four perfect splits per round, or 8, whatever splitter I had. So ya, 12 for a smaller one and 4 way..I dunno on an 8 way, no idea really. I can envision a 4 way but an 8 way would leave goofy sized splits, big and wide. Seems like they could be resplit again, don't know though, only seen vids of them. I do notice firewood for sale tends to be real large splits, larger than I like them. I use unsplit branch rounds and crotches if I want larger chunks.
I hand split and don't care, i actually enjoy the work and results from processing down a large tree, as I keep small branchwood to add to the split pile.
I have yet to see much difference in diameter of round when hand splitting as to difficulty. Anything large I either roll it in the tote box to get it back or if using the trailer and real big, quarter it or whatever and bring it back, then hand split. I slab off the outsides and work my way in all the time, so it could be 2 feet to ten feet, doesn't matter. Even rounds that have been quartered, I still restart on them from the outside in. I wouldn't as a rule try to mimic a mechanical splitter, too much work, work from the outside in and go round and around is MUCH easier than bashing down the middle and making pie splices like a mechanical splitter makes usually.
I get plenty of small diameter wood from branches and sapling thining.
