Comment by Someone
I think gradual rollout can use the same mechanism, but for a different readon: avoiding pushing out a potentially buggy product to all users in one sweep.
It becomes an A/B test when you measure user activity to decide whether to roll out to more users.
Has my CPU use gone up? No.
Have my error logs gotten bigger? No.
Have my tech support calls gone up? No.
Okay then turn the dial farther.