I'm with Crassius, after any install/maintenance, I'll routinely check on the tightness of recently reinstalled nuts...two, maybe three times, each inspection after a couple of rides. The nuts'll eventually get to a quiescent point where they're settled in and you won't have to worry about them again until the next time you loosen them. This goes for the head-nuts as well; all that vibration and heating/cooling cycling has a tendency to loosen things up at first.