I have a hard time trying to multi table. I tend to make more calls that I regret than good calls.
I think that it can be a good thing for someone who is just playing by "fast" math.
Personally I like to be way more involved in the games that I am participating in. I like the psychological aspect of the game. Trying to anticipate each players action.
Those that multi table, always tend to be running behind and tend to get into snap calling or run out their time bank. Either one is not going to be effective in a possitive way for that player.
Depends on the individual. It's easy to play normal, slow speed 9max tourneys on 8+ tables for me. if it goes down to 8 or 6max, and turbo, hyper of course less tables are suitable. Usually running different type of structures in the same time, so 4-6 is the ideal.
The fast math doesn't really stand for most of the multi table players. It's pretty easy to decide what to do pre-flop, most of the times. Later on, on the following streets it's getting more difficult, but you don't play down all the preflop involved
hands to showdown. Flop also not a hard one, turn is a critical, on the river often everything is in the pot, so nothing left to decide....
Are there more miss clicks, bad calls, run out of time, can't check the opponents, don't remember how he played in previous hands etc.? Sure, it is part of it. I don't mind that anymore. The other side, if you don't multitable badbeats can run for months+, so you get really disappointed about the game, if you multitable it doesnt last so long.
Most of the players take more attention to 1-2 tables all the time, where they went deep, have higher buyin, gtd, play the tourneys regularly etc. Some even mix it with other things, like sng, multisng, spin&go, but the main focus is on the tourneys.
Multi table players run out from patiance later, don't mind if someone purposely slowplay without reason. Need 2nd activity only at the beginning of the day and near to the end of the day, when less tables are running.
Personally what i hate, some rooms don't have option to click out from the table window straight away, if it jumped up (or you can turn it off only with the table pop up together...). Really annoying, if you play in 2-4 different rooms in the same time.
But it really depends on the person, i even know high stakes players, whose agree with your opinon, and they play only 1-2 tables, tourneys paralelly.