For me the main criteria is playing within your comfort limits. I play 4 x $25 tables at a time with a BR of $1600. I moved up from $10 tables at with a $700 roll about 3 months ago, initially playing 2 $25 and 2 $10 tables. I am now contemplating trying 1 0r 2 $50 tables in the 4 I play, but still don't feel comfortable enough yet, the thought of dropping $100+ in a session is not something I feel ready to face yet!. Some may say this is too conservative, but for me, if I'm playing even slightly scared, I won't play correctly.

With regard to whether 5% 0n each table is correct, I think if you are happy with your game and disciplined enough to avoid tilting when things arent going your way, then its fine. In my experience, its rare to be dropping $ across all 4 tables and when I do have a bad session, I try to limit the loss to no more than 2 buy ins. Once I hit that benchmark, I know I will be getting a little testy and prone to making questionable decisions, so I switch off the computer and go and do something else. I may not be making money as fast as I potentially could I know, but I'm also limiting my losses and heading off the circumstances where I will be prone to tilting.

Just my 2c.