Lot of variation here. I was always under the impression that lead 6's pooped out at about 40 and lead 5's at 50. I'd love some information to the contrary.
I do most of my hunting in a state that requires 7 1/2s or larger. For my 935 I use 2 1/2 ounces of 7 1/2 TSS through an Indian Creek and that produces plenty dense patterns in excess of 70 yards, although I haven't tested it on birds that far. In my Montefeltro 20 gauge I shoot federal 1 1/2 ounce of TSS 7s through an Indian Creek and it has solid 50 yard pattern density. Wish I could shoot smaller shot, but I can't.