I have flip up caps on all of my rifle. I really only use them when hunting in the snow to keep the objective lens free of snow, since the it is pointed up, or on both if it snowing.
If I have clear weather and no snow in the trees I take them off, they just take up time IMHO. If you have 3 seconds to make a shot do you want 2 seconds taken up remembering to open your caps? If all of my shots were long range I would use the caps all of the time, in the trees you normally don't have the luxury of time.
Darrell