Then, as now, no shortage of opinions...some contradictory frown

Lots here
https://docs.google.com/document/d/17__6nT2u4mP22we08yCBThQ_a-VtmOueW5CisK3c2To/preview

Already reviewed looking for specific advice regarding which barrel if shooting once (U.S. style) at inanimate targets and couldn't find anything. I do recall John Olin liked the left barrel first on skeet doubles as the recoil was into the face.

BTW: this thread has some neat vintage videos of live action target and pigeon shooting. Despite the vintage mount mythology, most of shooters look like they could have been at the 2016 Southern
http://www.trapshooters.com/threads/vintage-live-action-trap-and-live-bird-shooting.514889/

It is clearly shown that recoil from the first shot lifts the heads of several shooters well off of the stock

https://sites.google.com/a/damascusknowledge.com/www/home