I had to take down two absolutely enormous Douglas Fir trees on my property (> 36" base), and asked them to leave the wood rounds for me. I knew it was going to be a lot of wood, but even then, I was not prepared. I spent about a fair bit of my free time over the next 1-2 months just out there slowly working my way through the pile, and you're absolutely right - you get substantially better at it. For me, it looked something like this:

Stage 1: At first, I could chop essentially nothing, probably 60+ minutes per round as I mostly puzzled about how to make progress and got lucky from time to time with a round that split easily (fortunately, I had a nice splitting axe)

Stage 2: Then I bought some splitting wedges, and I used a handheld sledgehammer to drive them in to what I thought were the weak spots, and then ultimately pried open the log, to pieces that I could split more readily.

Stage 3: I bought a massive demolition sledge hammer (essentially a two-handed battle hammer) and used that to drive the wedges in after getting them started, and made a bit more progress on actually splitting the rounds.

Stage 4: After doing this countless times, you just a knack for reading the wood, and where it will / won't split. I reverted back to using just the splitting axe, since if you hit the wood in the right spots, it really just splits on its own.

Here's where I ended up, if it helps any of you:

- Start by establishing the fracture line that will be used to split the round in half. I would eyeball any existing line on the round towards the center, and use the axe head to mark a line, away from any knots , from the center to the edge. These two center-to-edge didn't necessarily need to be inline. They could be slightly offset, like hands on a clock.

- With moderate force, just repeatedly strike that line, working from the center outwards. You'd be shocked out how quickly repeated strikes widen the line, and eventually the wood's own weight almost causes it to fall apart.

- Recursively do this with the two halves: Draw the line from (what was the center), radially out to the edge. Repeatedly strike until these pieces have been halved.

- Continue this process until you have proper pizza wedges. At this point, it's pretty trivial to just chop the pizza wedge, from the wedge to the base, into 4 or 5 smaller firewood-sized logs.

I know y'all probably didn't care to read this, but this was quite honestly weeks of my life in learning this, and I couldn't find a great guide on YouTube or anything, especially for rounds this big.