Hickock45 made a number of YouTube videos several years ago in which he had an FFL licensed friend/acquaintance bring a Glock 17 with switch and then a Glock 18 with a pile of 33-round mags to his range. He could control it some, mostly shooting 3-4 round bursts -- using both hands, but nowhere near semi-auto. He's a highly experienced competitive shooter. I've little doubt he also did quite a bit of practice with them before shooting and editing his videos. Following his channel off and on is where I first saw a Glock Switch. Didn't think much of it at the time . . . and then I started seeing news reports about in the hands of gang-bangers several years ago in 2018 or 2019. Deja vu kicked in with the videos I'd watched on his channel.
I had personal experience handling an M14A1 and an M16A1 reliably firing in 3-round bursts. Took a magazine or two on the range as it is an acquired skill with trigger timing. You aimed slightly low and let the muzzle rise. You weren't going to drill them all into a 2 MOA circle or anything close to one. Getting all three onto a 2/3 silhouette at 25 meters was doable.
Glock 17+Glock Switch -- about 5-6 years ago -- IIRC on supervised loan from NC Silencer.
Glock 18 -- a year or two ago -- supervised loan from Silencer Central. His first video with it resulted in a broken slide near the end.
There is a reason they call it the 'giggle switch'.