I like at least 3 tables so I don’t get bored and play mediocre hands, back in the day I was 8+ and did well, but you lose the ability to learn the players at your table.
As I play mostly 8 and 9 max MTTs, the 4-6 tables are the ideal for me, however I agree, you lose the ability to focus for all tables and players same like playing only 1 tourney.
Otherwise, most of the time it takes 8-10+ hours to reach the FT bubble, and there are usually just few more phases, when I should focus more for one table, it rarely happens simultaniously on more tables, so I can manage it, even there are mistakes because of that, but playing on micro, low level, I can live with that, it is still more profitable than playing only 1-2 tourneys. Especially, I run out from patiance easier in that case, or I have to do next to the poker something else, as I can't just focus for the same tables sometimes for hours without any action, then comes the mistakes, too.
It was okay playing 1-2 tourneys, when I did not play everyday, just once in a week.