I'm looking at new plow shares and I see deep suck, flat, rib-flat, hardfaced/hardened, upset point, narrow cut, full cut, forged. Is this purely a trial and error selection or are there some general guides? 
Single bottom plow looking for average 6-8" depth (have a subsoiler if needed) some broken/disked soil, some sod,
I have sandy river valley soil, very few rocks and they are small.
The next town over has glacial till: rocks/gravel with loam making up the balance, all on top of hard pan(hard enough most backhoe operators just give up when they hit it, but its a few feet down)
Single bottom plow looking for average 6-8" depth (have a subsoiler if needed) some broken/disked soil, some sod,
I have sandy river valley soil, very few rocks and they are small.
The next town over has glacial till: rocks/gravel with loam making up the balance, all on top of hard pan(hard enough most backhoe operators just give up when they hit it, but its a few feet down)