Depending on ranges you can use a single load for different birds. Yes, 2’s may tear up some teal but will also drop geese. 4’s will drop geese at respectable ranges and be great for teal and other ducks. If you’re using steel at close range, improved cylinder is hard to beat. Pattern some loads and you’ll get a better idea. Pick a versatile load and you shouldn’t have to worry about changing out on the fly. I’ve come to rely on bismuth #4 for all my fowling inside 35yds in my 20ga.