Wow! I wonder how you divide your attention between all these tables? Even with the notfication sounds on - how do you know which table beeps? Or do they blink?
Would certainly drive me nuts
Notification sounds? LOL. I'll be mad in 30 minutes listening to these... so all you need is just some nice music. No table blinking, no auto-switching.
Clicking fast? This was easy for me cause I've played starcraft rts approx 20 years ago and was good at it. We used APM(action per minute) counters to pay attention and increase the number of effective clicks per minute to have better control of economy, surveillance and battles in the game. Many time has passed since then, but that practice of fast decisions and clicks helps a lot in everything that I'm doing at the pc.
Poker... all you need is comfortable chair, good setup with your monitors, so you won't have to spin your head, today you can buy one of those ultrawide monitors for such. And ofc you need to use keyboard shortcuts for bet/check/fold. If your strategy is loose, and you want to see the flop with wide range very often, then I guess that you have to be really, i mean VERY fast, if you want to control 12 tables... I've always played tight, so most of the time I'm just folding at all tables, it's really rare when you have action at 3 or 4 tables at the same time with 12 tables open, so it's quite boring and most of the time you're just pressing that fold button. I wasn't paying attention to actions of my opponents, HM2 did that job, and when it was action time I simply paid attention to the stats.
It might be hard for beginners to increase their APM to 120+ and keep it above 120+ for several hours in the row. But you know, our bodies are getting used to new conditions really fast, you need like 20 days to get used or to get rid of some habit. SO just practice in comfortable conditions and use condoms for safe poker.:motz: