The trend in clay shooting is to go to 1 ounce or lighter loads. The olympic shotgun sports limit skeet to 28 grams and trap to 24 grams. Roughly 1 oz and 7/8 oz in non metric terms.
FITASC is going to 1 ounce after allowing 1 1/4 oz for years.
I doubt ATA will change but stranger things have happened.
My pet load for SC is Remington STS/Nitro with Rem fig 8 and 1 1/8 oz of Lawrence Magnum. I use Remington 209 (Pattern here!) and 18 G of 700X.
I have experimented with 1 oz loads with a Rem TGT 12 wad, mostly with #8 in STS hull. 17.5 G of 700X. Worked quite well.
Most of my shooting lately has been 20 or 28 Ga. I am still diddling with the 28, need to shoot more