I played max 8 tables, min 6 and never had to use my time bank - even tho the Stars tables re-size well, I think 6 is the best for my 17" monitor - 7-9 is doable but tiny.
When I move my 20" Dell from the office to my study (when I get it set up) I will be able to play 9 at once.
Mind you the budget option would be 2x17" Monitors - you could play 12 comfortably for sure
2x19" or 2x20" and I guess you could play up to 18 though I suspect that really would be pushing it..see those FPP points fly though