The only time I can see for adding time for balls in touch is if you do not have ball runners.
The worst I ever experienced was an assistant referee in a game that was already 8-0 with the losing team down to 10 men and the losing coaching begging me to get the center official to end the game. He added 6 minutes, when I asked him why, he said "I don't want to cheat the kids."
A lot of referees at the high school level sadly, have no common sense.
