No the positions are fairly easy, after a bit you get used to them and automatically put your slide in the right place. 1st position is all the way up, 2nd position is about 1.5" down (1" usually on a Bb/F trombone), 3rd position is usually the bar on the slide inline with the rim of the bell, 4th position then top of the slide inline with the bell, 5th position a bit lower, 6th a comfortable stretch of the arm and 7th position a stretch lol!
starting in 1st, 3rd and 4th position is usually easier as you have some sort of reference point where you don't with the other positions, this is means playing scales starting in 5th position is hard because you have to make sure your starting note is in tune otherwise you put the other notes out, so a great deal of listening is required.
I noticed the other day that every time I play third position I will flick out my fingers on the slide and put the against the bell to stop my slide, so I know that is 3rd position
But you are always making little adjustments of the slide to get it in tune