Actually Rummer, I'm gonna back off and say "anyone" should shoot whatever works best in their scattergun, that they are happy/most confident with!
Was looking at a reloading manual that reminded me of some things, and lots to be said for #6's but also 7 1/2's, or visa versa.
I like them both, but would choose the larger pellet myself in a 20ga (or even 28 gauge) if tweeking the correct choke tube gave the right kind of pattern (in my gun). I already know for upland loads1220-1250 feet-per-second is all the VELOCITY I generally need, if I can get my shotgun to print consistent even patterns, at NORMAL RANGES.
I didn't always believe that, but I remembered I made one of my all-time great shots with a load of 'sixes.' Maybe i can elaborate on that later, but best thing I can tell anyone is to take the time and test-pattern what loads they want to use IN THEIR gun, and then choose what they think they'll be happiest with.
Also keeping a hunting log and record of what works too (shots fired under wharever conditions, and then game taken) could help indicate successful trends to be followed as well.