Somewhere out there in the interwebs, somebody is wrong about practically any topic you can imagine.
+2
Problem I see is that there are WAY too many people who need to quit regurgitating old/outdated information based solely on their Google skills, what they heard some place, advice from their beer drinking buddies, etc. This goes for about every topic out there and not a single day goes by in the shop I don't get a call from someone who buys in to all that Internet BS.
The "basics" of file size and it's use hasn't changed since I started cutting firewood way back in the early 1970's.
Back then it was easy, we bought only saws that used .375", full chisel. So we only had to buy 7/32" files. In more recent years we've moved to smaller saws and .325" so have to keep 3/16" files around, and even more recently 3/8LP so now we have 5/32".
I don't use Stihl chain and even when I incidentally ended up with a loop or two of it in .375" it was sharpened with 7/32" files and never grumbled much, but IF that was the main deal around here I would invest in the recommended files for it.
The following comment is certainly not meant to confuse anyone, but I know folks who switch to the slightly smaller 13/64" files on Oregon .375" chains when they get very close to the end of their life expectancy. I don't bother with that here and they seem to keep cutting just fine as the teeth get smaller using the 7/32" files on them......Cliff