In my first game... after telling myself pre-game I wouldn't be a ball-watcher, I end up ball-watching into my partners primary and see players fighting for control of the ball in the first half.
I blow my whistle for a held ball -- only to be told by my partner it was two players from the same team going after for the ball
. I ended up calling a travel instead and wondered later if maybe I should have just gone with an inadvertent whistle.
At least the experience was enough to help break me of my ball watching habit.