:rolleyes: 8 to 10 rings per inch is more than sufficient.
Not sure about Central KY but, I find osage few and far between with rings like in Eric's pics here in Southern Ohio. There may be some here but not where I can cut'em. Sometimes you have to live with what is available.
The tree in Eric's pic appears to have been growing in the open sun for about 17 years. As the brush and competing trees shaded it out the rings began to get smaller. Real nice wood.
With 8 to 10 rings per inch, rough shaping the bow is easier than those with 1/4" rings as you can use the belly rings as a visual to get an even tapper on each limb. This makes tillering easier as you get real close to even before putting it on the long string and tiller tree. I find I get so close with this process sometimes I can go straight to the short string and about 4" of brace before fine tillering begins.
I only measure and mark the handle, fades and length of limbs. I rarely mark depth or thickness because I use the belly rings as a visual to get close to my target weight. At 8 to 10 rings per inch I end up with about 4 rings at the tips of the limbs. (I'm talking flat bow design here)
I can't see early age man cutting your tree with stone tools and then discarding it beacause it had thin rings. Their 1st thought would probably be something like,,, where'd I stash that bundle of sinew!