I like to be 25' minimum... sometimes 30'. That will probably change once I get a set of LW sticks, though... 25' will probably be it. A sixth stick won't be worth carrying IMO.
Chad, I've used screw steps for a long time. They get the job done and work very well... But I'll tell you, compared to the climbing sticks, the screw steps are terrible. Yea they're cheaper, but they're also a pain in the ass to carry, screw into the tree, and remove. I'll pay extra to make things easier, any day of the week. I watched fluteman climb a tree, hang a stand at 23-25', and was ready to hunt in 4 min 33 seconds... Any doubts that I had before then vanished immediately.