Bill
The guy referenced in the post below yours (Buckin Billy?) , in other videos has expounded on his experience that "unequal tooth profile" does NOT contribute to crooked cuts. His position is to sharpen each tooth for it's own value, and set the rakers to suit (with a gage), Worn saw bar grooves is another issue.
I practice using up the chains regardless of unequal teeth, And I have favorable results. (When you hit stone or metal on just one side of the chain, things go south in a hurry.)
I use that multi- file guide that Stihl sells at present, but I used to just free hand the file and use Carlton file-o-plates to hit the rakers.