Our drawing have them called out both ways. Just depends on who did the drawing. Our purchasing department doesn't have any issues ordering either way it is called out.
i think that mentioning the thread length in fraction is a good idea, as most of the vendors from which we purchase the hardwares prefers fractions insted of decimal.
I like fractions as well. The only issue is if you want to save the file as this, it won't let you because of the forward slash in the file name.Then you have to use decimals.
We would call them out as they are listed in McMastercarr
4-40 x 3/8" BHCS since that is our vendor.