I have re-checked the documentation and compared our actual traffic use. One of our FG uses max 4,000 sessions per second with nTurbo of 60% - 80%, the other one uses max 2,000 sessions per second with nTurbo of 40% - 70%
Depending on the documentation, if I looked up the right section, concurrent sessions are 3 millions, concurrent sessions are 280 000.
I have 7 subnets on each FG, and all of them uses internet, not much of heavy internal policy or something
I guess it would be enough, what do you think?