Just did the border bounce at Mae Sai. I'm on a non-O multiple entry visa. Before stamping out I asked if I would be allowed back in, wich after checking documents (passport, non-O visa and vaccination certificate) got told would not be a problem. Myanmar side got asked how long I wanted to stay, reply 5 minutes. Had to pay 500 Baht and got stamped in and out no problem. Back at the Thai side handed over passport with non-O visa paper copy and got stamped back in 90 day extension no problem. All in all the whole proces took me 10 minutes.
Have a good day all