I have tried multiple tables in the past but didn't do that well I think the highest number was about 5 or 6 at the same time, I know you can have them on top of each other and the table requiring any action from you pops up to the top, but I found that terrible because you get a table popping up, that needs you to Call, raise or Fold and just as you click on any button another table comes to the top and you click on the wrong button.
Tiling tables did work for a while and 4 tables spread over the screen was great but once you get more the screens are too small for you to watch all the action on other tables. I eventually gave it up because at the very best I only ever broke even, and at worse lost every game due to miss-clicks etc.
Perhaps a HUD may have been a useful tool, and I did look into buying the software, but as I preferred playing Live games over On-line tournaments I quickly dismissed the Idea, because there is no chance of using HUDs in a Casino and I didn't want to become dependant on one.