Here's a simple little tuning exercise that's not as easy as it looks...
Some players, once they own that trigger, begin to believe that all positions beyond 4th are alien territory. Thus a simple gliss to 6th seems to give trouble.
After finding 6th, you would think it a simple matter to gliss back to 5th accurately. Nope!
I think there are several reasons for this..
1. When we do our beloved Remington long tones, we are always measuring out from 1st position. Accurately "measuring out" is something we do a lot, but "measuring in" is something we don't practice. Maybe we should do that famous Remington pattern inverted.
2. (disclaimer, this is pretty speculative, I may have it wrong)
Beyond 4th position, the elbow begins to have to extend beyond a right angle and seems to be less accurate.
Anyway, try those glisses out with a tuner (look first, then listen), see what you think.