Marty,
I dry a LOT of blanks for woodturning. In my experience, drying log sections is generally a waste of time and wood. Due to the way wood shrinks as it dries and the fact that most moisture escapes from the end grain, a section from a tree will almost always check, crack, and maybe even split down the side well before it's dry. The amount depends a lot on the species and the drying conditions. Some domestic species like eastern red cedar, sassafras and walnut are much more stable than wood like black cherry, bradford pear, oak, and flowering dogwood.
Some of this depends on the individual tree. For example, some cherry will start to check soon after it's cut. But once I had to take down a large cherry tree and it just refused to crack! I have some sections that survived over 10 years later. One chunk left on the ground out in the weather eventually started to rot but never did crack. You never know...
Note that wood generally shrinks about twice the amount along the rings as it does along the radius - that can create large stresses which can pull the wood apart as it dries. You can prevent some of the tendency to crack by first cutting the log section in half with a chain saw, down the pith, or better, remove an inch or so containing the pith. This may not prevent end checks but can minimizing larger cracks by letting the wood warp to relieve stress as it shrinks. Note that a half of a log chunk will probably be wet inside for years so it is still recommended to turn them as soon as possible.
If wanting to turn green wood, the general advice is to not save more log sections than you can reasonably rough turn in a few weeks. Seal the ends well (I use AnchorSeal) and keep them off the ground and out of the sun. The other John Jordan, the famous woodturner, recommends to acquire the entire log an keep it in one piece, again stored off the ground and out of the sun. When he's ready to turn a piece he goes out and cuts 6" off one end with a chainsaw and throws that away, then cuts a blank and turns it immediately. Besides keeping it in the shade, he doesn't bother keeping it out of the rain.
If you set the log section on end on top of another piece of wood, concrete, or plywood, that end will stay wet longer and be far more protected from cracking. If I have to keep log sections for more than a few days I like to make a stack so each piece protects the end grain of the piece below.
I mostly turn dry wood so I always cut green chunks from a tree into smaller turning blanks as soon as I can. These have a much better chance of surviving. I keep the pith out of the blanks and seal the ends well before putting on the shelves to dry. I mark the species and date and for a batch of similar sized blanks I often weigh a piece or two and write the weight for monitoring the drying progress. I primarily use the shop bandsaw for this but for large blanks I sometimes use my bandsaw mill. I've cut and dried thousands of blanks this way with good success. For example:
Attachment 450599 Attachment 450602
Any carving I do is also from dry wood. Some people do rustic chainsaw art using the wet log but most I've seen had cracked badly after some years.
Another option for drying green wood from a log is to have it sawn into slabs then stack and dry the slabs. I sometimes saw slabs from 2" to 4" thick and dry the slabs, fine for platters, some bowls, turned boxes, etc. Since the slabs are wide and the amount of end grain is relatively small, more of the wood in properly stickered slabs is likely to survive. It is still recommended to seal the end grain. Slabs can also be stored vertically, at least for the 1st phase of drying - in some species you can watch the water run drip out of the end.
Another option for triage for rescued wood is to submerge them in water. This is called "ponding" and will preserve chunks and logs indefinitely if the water isn't left to stagnate in the summer. Submerged logs and beams have been recovered in good condition after many years. A fried of mine used such beams when building his timber framed house.
Fortunately, it's usually much better to cut and store logs in the winter than in the spring when the temperature is warmer. Your friend can probably delay processing the wood for a bit.
JKJ
