Hardest day I ever had in the marsh, we caught a migration when the Pintail limit was 1 bird a few years ago. Wife, youngest son, and myself limited out in Pintail obviously in the first split second when the shooting time alarm went off. After that we had a flock of 20-50 birds or so descend from the sky and hit the decoys probably about every 60 seconds, tops, for the next few hours. For the first hour or so I eyed everything coming in, sometimes there'd be a few Widgeon mixed in but by the time I saw them and tried to coach the wife and little big kid to shoot the correct ducks they were passing by and too late. We got so desensitized we had a couple solo redheads just fly by and we all just looked at them and watched them go lol. After about an hour I got tired of it and we just kicked back and watched birds and got cell phone videos and such until we got bored. Dog was super pissed.
Same general area there's a group campsite where a lot of duck hunters and bay hunters setup camp and a group of probably 15 of us were hanging out around somebody's campfire and a young dude started telling a story if him and a buddy shooting a couple hundred Wood ducks. He said they just kept shooting and just kept coming like you mentioned. They finally ran out of shells and started hauling them back one limit at a time. Everybody was just kinda standing there in disbelief... He said after probably a dozen trips or so the GW checked them with their limit and asked about where they were hunting and they only had a limit with them so cleared them and they went back to their truck and left without retrieving the rest of the dead birds. Everybody just turned and walked away and left him standing there by somebody else's campfire all by himself, it was super awkward.