There's still some correlation to quality. Personally, and I think my friends all do this as well, I have a default rate in mind that I then adjust up or down d

There's still some correlation to quality. Personally, and I think my friends all do this as well, I have a default rate in mind that I then adjust up or down depending on service. Usually criteria for adjusting up is whether the server has a noteworthy level of service or whether I'm being an unusually needy customer. Adjusting down usually requires something fairly egregious.