Agree with what others have posted about balance, the feel of a gun, as the important part and I believe barrel length while part of that is not the dominant characteristic.
Good shooting is habit and repetition. There are a few talented people who can pick up just about any normal gun and shoot it well. Most of us get used to a particular feel and finding it works for them stay with it. The more you use that set up, the better you get, then the more picking up something different feels not quite right.
When I started out as a kid I shot a German 16 BLNE 28 inch with a cheek piece stock. I grew up with it and thought it fine. Unfortunately when I left home for the Army my Dad kept his gun and I had to get try to get used to a Fox Sterlingworth 16 with 28inch barrels and alot of drop in the stock (not a good fit). I brought a Browning Citori with 24inch barrels (too many sporting magazine articles on the virtues of short barrels for grouse) which I shoot better but never well. It was whippy and in hindsight it was more because the gun Center of Balance was too close to my trigger hand.
Over the years, and many gun buys, I figured out what worked for me and everything I was good with had 28inch barrels (but also a balance point about the hinge pin) One day I ended up buying a 16 with 27in barrels that happened to fit me perfectly and its balance was just right.
I fooled myself into thinking 27in was the ticket not paying attention to the weight and balance as more important.
Lately I got a Purdey project with 26inch barrels and after playing with the balance got it adjusted in to near prefect for me. Over time I have learned what matters for me on changing guns is the weight and balance not the barrel length.
We are creatures of habit. I shoot 16 most of the time and the look down the barrels of a 12 feels odd to me as it seems so very wide. That feeling is perception. If I shot 12 ga almost exclusively then a 12 would seem just fine.
Barrel length, outside of extremes, is subjective when looking at 26 to 30. Subjective matters to the shooter and when you find what works consistently for you stay with it.
