IC and mod in my Beretta 693 20 ga.
I won this gun in a pheasants forever raffle a few years back, previously I mostly shot a Rem 870 Lw 20 ga with a fixed mod choke. When i started shooting the Beretta and put in the IC to start the season, I expected to get more hits on birds, but also more cripples/runners.
What I found instead (once I learned to shoot the thing, it shoots a little high which I've grown to like) is that I get more hits and more birds dead in the air. I think the more open patterns result in birds with more hits over the whole body, and a lot of my birds with the fixed Mod choke were just getting hit by pattern edges. For a while I was screwing in different chokes depending on time of year and cover conditions, but now i just roll with the IC/mod and kill birds without overthinking it. The 2nd barrel with the mod choke is almost exclusively used for anchoring birds hit with the first barrel, though it does get used for the occasional double.
I hunt over a couple labs, mostly in cattails and heavy cover here in Alberta. But I've hunted MT and ND a fair bit too.