For most of Frankenstein's working life with me, it wore a cut down barrel nominally 21". Its original mission with me was as a turkey gun.
If you're coming in late, Frank's my overpublicized parts 870.
While the short barrel works well as an all around candidate, its blast with goose loads and 3" loads in general is impressive.
The 23" barrel now on Remington's turkey guns is probably closer to optimum as a GP barrel, but I like more than that for clay stuff and waterfowl. A 26" LC barrel recently purchased here would get the nod as minimum these days.
I note that as I age, I tend to avoid extremes of all kinds, including very short barrels except for defense. A better setup will be a short barrel for defense and slugs and something 26-30" for wingshooting and clays, IMO.
HTH....