SFO 737 FO here and was on reserve until this past February and there would be at a minimum of 2 and sometimes 3 FSB’s a day, usually in the afternoon and evening. As a poster above mentioned they will make assignments out of order so knowing where you sit in the silo is imperative as well as knowing the contract. I received a call late one night for a short call the next day knowing full well that there were two pilots ahead of me in the silo. When the scheduler tried to give me the assignment I inquired about the two above me. She told me that they both had one SC each already and that I had none so it was going to me. It was at this point that I informed her that per the contract a pilot could not be bypassed until they had TWO unused SC or FSB assignments. She put me on hold came back 30 seconds later and told me that I was right and I would not be given the assignment. This is the kind of crap the will try and pull. As mentioned above, know where you sit and know the contract. I’ll also add that I was on reserve for nearly six months which I realize really isn’t that long but over that period I can count on one hand the amount of times they left me alone on LSR. I was either on SC, FSB or out flying.