Comment by AngryData

I think it very much depends on the wood too, the species and how seasoned it is and how dry it is. Some chunks you can hit it almost anywhere and it will cleave across the entire block, but other woods you will hit a half inch in from the edge of the bark and the board will split under the blade and let it through, but leave a half inch near the edge unsplit that the axe handle hits with full force. Do it enough times and the front edge of the handle can get messed up.

Sometimes you will see wire or something else wrapped up near the top of the handle for that reason to help protect it a bit. But if you get enough practice you can reliably hit with the bottom half or quarter of the axe sticking out of the log so that can't happen.