I can play 16 ring games at once with a set strategy, but I lose, it's just too many for my level and experience. I can play 12 tables with a short stack strategy and show profit. I also tried playing 6 sng's at a time for 2 hours opening another one as soon as one finished, all 1$ ones, and showed profit, and I have no HUD atm either. On FTP when I play just one table I always search the player to see how many tables they are sitting at, and alot of times most of the table is sitting at 4+ tables, and some people with like 12-16 for sure and I have seen people playing more I think, but usually 16 is max I see. If you search youtube for multi-tableing ,you can find videos with people playing massive amounts of tables it's just crazy how many some people play.
I hear you gotta find your medium, you see how much money your making at a certain limit and increase the tables 1 by 1 until you are making the maximum money per whatever it is, bb/100 or hour, I forgot. I hear that your win rate will go down per table for each new table you add, but overall winrate can go up.
ex. you make 5 bb/100 playing 1 table but if you play 2 tables u might make 4.5bb/100 at each table, so 9bb/100 is better than 5bb/100 right, and if you add another ne for 3 tables and make 4bb/100 at each one then that would be a total of 12bb/100, get the idea?
But as you add each table, you have to make multiple descisions faster, and be able to multitask, so that's why ur bb/100 will go down. Eventually you can add so many tables that ur bb/100 will go down on each table so much that you will be making less money than if you had 1 less table or tables, so thats what I mean find your medium. You want to find where you are making the maximum amount with the most tables, without starting to hurt yourself with too many.
Then again multi-tableing is prolly not for everyone, and some people can only play 1 table at a time, you just gotta find what is right for you.
I usually just play 6, because that is all that I can see at 1 time on my laptop, without them overlaping, and since I dont have a HUD atm I take ALOT of player notes. I can go to my desktop pc and play 12, and see em all at once, but like I said earlier, when i do that I just play a set strategy and its SSS, and pretty boring grinding like that imo, but it does generate a good amount of rakeback it seems. And most of my player notes are on my laptop anyway.