Let me add a bit on this subject..
I was taught many years ago the art of making a haft, and hanging an axe. I was taught by men who depended on their axe for everything on a daily basis here in the hills of Appalachia.
Back in the day, a new haft was more commonly made in the winter after the sap was down, from green hickory, and ONLY the sapwood was used. The wood was worked green because it was easier to work, seasoned hickory is HARD to work with any hand tool. While working the green hickory had its benefits, it also had its pitfalls..
Green wood naturally shrinks as it dries, so hanging an axe on a green haft will result in a loose head sooner than later. The way around that problem was to roughly shape the shoulder, then use the hot coals in the fireplace to season, and temper that end. This was done by placing the head end of the haft over hot coals, and turning it to keep it from burning. Steam and water would boil out of that end of the haft, creating a surprisingly seasoned shoulder that could be fitted right away. When the haft was close to the preferred profile, it was scraped to perfection with a burnished metal scraper, or, more commonly a piece of glass. The rest of the haft was flame tempered over the fire as it neared completion. Although usable, the swell was generally left rough and oversized for a few months so the checks that would appear in the end grain could be removed with the final finishing.
The next problem was, as green wood dries, it tends to warp. Can't have that in a axe haft. To help eliminate warping a good straight grained tree was selected to split the haft staves from. If the grain is perfectly straight, it is less likely warp because of short grain run out. The other thing I was taught...wait for it...shape the haft with the grain running horizontal to the pole, instead of what is these days considered to be the correct way..vertical. The reason for this.. . the haft won't warp against the grain, only along the grain. Its like quarter sawn lumber, it expands and contracts more in thickness than width.
With that being said.. I have an old Kelly perfect that was given to me a quarter of a century ago by a friend that it was issued to in 1939 when he went into the 3 C's. I hung it as I was taught, with green hickory, grain horizontal to the pole. I use it regularly, nary a haft issue after 25 years!