As daft as it sounds, I feel I play much more optimally with more tables at the beginning/middle of my sessions. More robotic you may say, but I think early stages of the tournaments, you don't need to be anything but robotic in your decisions as most are very straight forward if you have played a lot of tournaments. As the tournament gets deeper and deeper, your tables start to dwindle anyway after busting, so I can play and focus more on my deep runs and feel much more focus when one or two tabling deep runs as opposed to early stages.
I can follow the action more closely one tabling even from the start of a tournament if I really wanted, but I find myself getting really bored, start browsing the internet, forums etc so ultimately my focus isn't 100% anyway or I start doing something even worse by playing more marginal hands.
I feel I'm most focused when I have around 10 tables at a time.