Like many here, I have also shot competitively, and in regards to gun types, barrel lengths, LOPs, etc, have just let the gun(s) lead me to the right choice for the specific discipline.
The vast majority of my career was box birds, and a couple of guns evolved into winners for me.
The Perazzi P-gun was the "get it done" top choice, but there were a couple of Parkers that served as well. In Particular, a 30" Vent Rib GHE pigeon gun that was owned and used extensively (and modified extensively) by a fairly well known pigeon shooter from yesteryear.
Around 2001 I started shooting registered sporting clays. My first registered shoot was at the Nationals.
Started in C, and worked my way up to AA, before the crash of 2008 sent my money and assets into the wood chipper.
Anyway, the hands down best clays gun (for me) was a custom built Beretta AL 391 trap gun, with a 30" barrel.
Not to plug an Italian on a Parker site, but the long barrel was incredibly effective on the long complicated targets that you
HAVE TO be able to break in order to win a big shoot, which I did.
Never shot a 100 straight in SCs, but did manage a 99x100 once, and did make HOA at a major shoot, that included Jon Kruger, and approx another 40 Master Class shooters.
A 98x100 on an extremely complicated course with some targets break points at 60 plus yards out. 300 shooters, so no pressure ;-)
In my opinion, and I do have an opinion on this, long complicated targets are easier to handle with long barrels, guided by a light easy input on the forend.
You break these targets with your sight picture, in addition to your gun movement. This, IMHO, is just a lot easier to execute with long barrels. Your mileage might vary.
If I can work up the courage, I might post some pics of the GHE, for S&Gs.
(Shoots & Giggles)
Just to show what a highly modified Parker pigeon gun looks like.
I will post a NSFW so that children and small animals are not emotionally damaged.