Dear Urist McBoltLoader,
I'm glad you finally got around to loading those ten crossbows into that weapon trap. I am! Really. However, why have you decided that the best course of action is to load ten crossbows worth of ammo into it... one bolt at a time? Is this some union policy? You don't seem to have any kind of guild I'm aware of. And yet, you continue to run back and forth, to the weapon trap and then back to the stockpile, dozens of times, each time loading a single bolt into the trap.
Now, I know what you said. Crossbowmen are useless! Not only can you not get them to shoot at the targets half the time, but in real combat their first instinct is to try and use their crossbows as hammers! A ha, said I, but if we use traps then we have a use for all these bolts I made!
And yet you somehow have managed to find a way to make this take longer than my desire to surround the entrance to my base with masterwork steel spiked balls. Why exactly are you loading the bolts to a trap with ten crossbows in it individually? Even worse, you're talking the bolts out of random piles of bolts, meaning lots of them now have strange numbers of bolts in them!
Shape up, or I'm going to give you a 'dwarven haircut'.
edit: I have found that actually, what the dwarves are doing is taking a stack of bolts, carrying the full stack to the trap, putting a single bolt into the trap, and then re-storing the now 1-bolt missing stack of bolts back into the stockpile. So they're creating numerous extra hauling jobs for no reason!