Roy,
I ran my load thru Exbal at 4800 asl at various temps. I have found that the humididty doesn't change to much here and base it at 40 all the time.
Next, I set my chart based on 4800 ft and 50 degrees. A good average for all the situations that I will be shooting my 243.
I can run up to 7000 ft. 20 degrees after coyotes, etc. and only be 1 inch low at 600 yards and strong 4 low at 1000. 99% of my shots are under 500 yards on Coyotes.
On the other hand, I can shoot PD's or control work on Predators in the summer at 4800 ft 90 degrees and I am only shooting 3/4 inch higher at 600 and 4.1 inches higher at 1000. Both will equal a dead coyote.
So, to answer your question, I just found a "happy medium" to base my dialing off from and will adjust a little as needed.
Not doing any BR work or paper punching or I would be alot more critical and have multiple charts and have shot at all conditions to make sure they are accurate.
I have found that most BC's of bullets I shoot are just a little high. After slight correction, they run good thru Exbal.
Hope that answers your ?