I only shoot #2s for everything from teal, mallards, geese and pheasant. Late season I switch to 3.5". Nothing drives me more nuts then half boxes of shells rolling around
2 3/4 #3s for ducks. Bought by the case because they are a bit harder to find. I shoot 2 3/4 SO much better than 3in shells..almost night and day. The ducks are just as dead and I don’t start getting a headache and flinching half way through the morning. This is with a fairly heavy sx2 auto loader..I can’t stand to shoot my 870 any more.
30ish ducks shot so far this season, majority with steel 6's. a few 3's or 2's for 3rd shots. 50% blue wing teal, the rest a mix of 7 species big and small. I'll continue to use mostly 6's over water, especially when solo. As we start field hunting, I break out the 1's & 2's. I do use bismuth and tungsten here and there as well. 5 roosters so far this fall with 20 gauge hevi XII.