When I say “hatchet”, I mean “small axe”. I definitely find logs split easier when the hatchet is blunt, the edge follows the grain rather than trying to cut its own route.
I only need to convert approximately one log in thirty into kindling and the rest are burned whole, so I can afford to be very choosy. Careful selection makes the job a pleasure rather than a chore.
Only very rarely does the hatchet fail to split the log with a moderate blow. In future, however, when this happens I will use your turn-axe-through-180-degrees-in-mid-air trick. Now you point it out I can see that the log weighs more than the hatchet so it makes sense to use that extra momentum to my advantage.
Another thing : Wood naturally splits as it dries, therefore I assumed that dry wood wood be easier to split with an axe than fresh wood. It took me a long time to work out the opposite is true. I think the wood fibres bind more tightly together as they dry, but what ever the reason, I now split my logs as soon as I get them.