I bought the .010 and .012 sizes off the tool truck to set armature air gaps on magnetos. (I work with small engines professionally)
I have used a long .002 to check piston skirt/cyl wall clearance on Chevy pistons in a 350 I built at Tech. School back in the day. (At least I think it was ,002, its been a long while.)
I would think an entire set would be handy for other uses as well.