not sure if it matters between MTT/SNGs and cash games? I like to play 4 cash game tables at a time. I can keep all of the tables on one screen and its easy enough to keep up on the action. I think I play way too many hands pre-flop, vs some of the other players that play 10+ tables at once. Don't use any additional software, etc. but rely on keyboard/mouse which probably slows me down a lot.
You should check out this video where bowlboy is playing 24 tables at once. He is the real expert on multi-tables. Not sure if he is using software to tile like this?
http://www.pokerforum.ca/f6/finally-made-vid-25060/