I ususally hunt 15-18 feet and have had a lot of success. In eastern ok there is a lot of thick woods and 15 feet is usually high enough.

Any height is too high for me. I like to keep both my feet flat on the ground.

If you decide to hunt the ground or 25 feet high, remember to cover yourself. Both visually and your scent.

Id say too low is where your stand is directly in the deers line of sight on a horizontal plane. I think it is better to be at least 8 ft. off the ground if possible. My stands average approx. 13 feet.