SFO T2 is one of the terminals where CLEAR has been least useful for me.
At most TSA checkpoints, the bulk of the Precheck line is before the ID check, with just ~5 flyers between the ID check at the x-ray at any given time. However, SFO T2 often (but not always) has it flipped: there's a very short queue before the ID check, with quite a long queue of 20-25 people between ID and x-ray. In this scenario, CLEAR saves no time (or even is slightly slower).
And don't even get me started about the numerous mornings SFO T2 has had the "K9 pilot program" that makes this even worse. A CLEAR employee escorts you through the *normal* (not even Precheck!) security line so that you can get sniffed by a K9 dog, before they then tell the TSA agent at the ID check station that you're CLEAR and can skip that step. Takes about 10 minutes of a CLEAR employee's time so that they can have a 2 second conversation to save you 5 seconds total, and that's it.