Imo , 23to26 is ideal , any shorter and you loose velocity, and you have to work harder to get a good pattern
Over 26 and you start to notice the weight, I will say this some of the very light import autos like a bennelli, franchi ... the 28 inch guns weigh alot less than most guns more like 7 pounds on the nose and point real sweet you wouldn't know thier was a longer barrel on there by holding it up