Back in the day you could specify teeth size if you ordered a knife. some knives have smaller teeth as a rule, like a model 1. 14's, 15's, and 18's often varied in size, but prolly in the late 60's to early 70's larger teeth seemed to be the norm. Less work to do larger teeth.
I've always wondered if small teeth or large teeth would perform better on aircraft aluminum. Seems like small teeth wouldn't hang up as much - like the small teeth on a hacksaw.