SFO Hours
Just went thru security at T2 in SFO. Got the three beeps but PreCheck line was cordoned off. The guy checking the ID has said that he starts work at 6pm and never has seen that line in operation. I doubt he even knows what the three beeps mean.
After going thru the machine, I asked another agent about the hours and she said that the Precheck line closes at 5PM.