I could probably handle at least 4, but I REALLY am not a huge fan of play more than 2 at once.
The more tables you play, the more focus you have to spread.
Mass multitable is not a skill that you can develop imediatly. It comes in time. I probabely require the same amount of focus playing 12 table as you need playing 2 tables.
Most of my decisions are automatic because they are standard for me now. I require focus only at 10% of the decisions i make.
Of course this is only at micros. There are no situations i cannot handle because i only target the fish. When i play 10NL or 16NL i have to drop down to 8 or 6 because i have to deal with a lot more regs. Not the best regs but still there are a lot more decisions that require focus.
Every one of us started at one table. We increased the number of tables in time. There are a lot of things a player need to improve at. Probabely the best books that explain and advise a player on how to become better are "Treat your poker like a business" by Leatherass and "The mental game of poker" by Jared Tadler. You not only need to learn poker but you need to improve a lot of other things. The cruel reality is that 99,99% of the good poker players of the world made it where they are by putting up volume and by increasing their lvl little by little. There is no way around and that is a fact. There is no shortcut. The players that you saw on TV like Negreanu, Helmuth, Ivey etc are special. They are like Messi of poker. They made their money being the best at live poker playing high stakes. They cannot multitable at
online poker but they do not need to anymore. After all there are not too many players playing at 100000NL. They cash huge promoting different
poker sites.
For a new poker player that is not possible anymore. If they dream at winning the
wsop than 99.9999 of them will keep dreaming untill they die.
So what is left? Mass multitable and a lot of work at your
poker game, mental strenght, phisical strength, I think anyone if who is not retarded can do that. If someone is thinking that playing 1 or 2 tables will get him somewhere, he is wrong