I have a custom ret 40x comp, I range from high to low and simply bring the target into focus looking for perfect clarity.
Say a target is 50 yards I start at 55 yards, I will the go to 52.5 yards and bring it into focus. I then do it once more at say 52 yards. Worse case I end up dialing 49-51 yards.
Last week after checking over my kit for my return after a 4 year layoff I used a rangefinder and a target was 50 yards I ranged it with the Lupe 30 times and as above it came in 24 times at 50 yards 3 times at 50.5 yards 2 times at 51 yards and once at 49 yards. So it's not to bad.
I have had big nikko's, still have a Burris ra 8-32x44 and a bushnell elite 8-32x40. I have to admit I still have a soft spot for the bushnell it's a great scope, optically I really like it.