My best clothesmaker gets into a strange mood and runs off to collect junk. After about five items he stops. I look through his list of wanted items:
cut gems
rough gems
wood
wood
shell
cloth
leather
blocks
Well, he's already got 2 wood, some cut emeralds, a shell, and cloth. Got leather of just about every type imaginable, so that's not it. Rough gems? Damn. Looks like I'm screwed.
This guy's already 2/3 of the way to Legendary and I don't want to lose him, so in desperation I start making blocks out of glass, metal, anything I can find (I knew I already had light and dark stone so I didn't bother with those). He won't budge. In resignation I call up the army in case he goes berserk.
Some time later I glance by the work area and find he's missing. I hadn't seen a "goes insane" message so I start looking for him. He's making a beeline for the trade depot--the caravan just left, so maybe strange mood dwarves only take trade items after the traders leave? Nope, he heads right through the depot and into the small work area beyond, ducks into a mason's workshop, and pulls out... a freshly carved set of plain rock blocks.
I had finally managed to use up my stockpile of rock blocks without realizing it, and only made more as practice to get my secondary mason up to legendary. Thereby narrowly saving the clothesmaker I had nearly doomed to insanity.