Here in my county... our elevation ranges from around 600' (river bottom) to 1100' (highest ridges). We do not have mountains.
It is quite rare to find seng above 800' in elevation. It does happen, mostly on tall hillsides that pretty much face back due north... or up at the heads of some hollows where it is facing back due north.
But in the average hollow around here... you are going to find the bulk of it below 800' and it will actually be somewhat sparse between 750-800 but really start to pick up in the 750 and below range.
This right here is a very common situation here in my county. If you start out at the head of the hollow, working your way down... at the higher elevations... you will see a gravel creek bottom, perhaps no water yet, and you will see a lot of muscadine, hard green briars, sasafras, poison ivy,... then as you work your way down the hollow you will eventually get down to that 800' elevation range and your gravel creek, will turn to slick rock bottom... and then you start seeing more seng companion plants, MHF, Bainberry, etc... and often just a little more down the hollow, there will be a drop in elevation (that slick rock creek, will go off a little waterfall or two)... could be only a 10-30' drop elevation wise... and then BOOM... the seng shows up big time.
I have seen that situation play out hundreds of times in many many hollows here in my county.
I think in my case at the higher elevations, you have mostly sandstone, but as you get lower you run into the limestone bedrock, and start having limestone outcroppings... and when you get there, that is when the seng shows up.