Yeah, when I started sharpening a lot of chains, I was obsessed with finding and following the exact specifications, angles, etc., for each chain type / size / brand / etc.
Then I talked to some technical reps, and discovered that these are more like ‘starting points’ for ‘general use’.
Not bad, but, with experience, many people will use different angles, and sometimes different file or grinding wheel sizes / shapes, for different types of wood (hard vs. soft), different saws (power level), types of cutting (limbing vs. bucking or ripping), personal preferences (speed vs. longevity), etc.
Good to start with the basics. But don’t be afraid to experiment a little, and see what works for you.
Philbert