I'm up to 4 self assign but most of their shops I do are for the same client.
Probably 50 shops for the same client this year and it hasn't changed.
What I do know is, once I submit a shop, I can then self assign another shop.
And, you can always request a shop if you can't self assign.
Bigdaddy,
I'm guessing you do multiple or different clients for ISS. I do two.