It's just so variable. On a trip a couple of months ago, Service was mediocre to abysmal on 3 of 4 legs in F but exceptional on one of them. RNO-DFW, the flight attendant not only served PDBs, including mixed drinks, but also offered a second before departure. As it's about 3 minutes from leaving the gate to wheels-up out of RNO, the FA advised that we could hang onto our drinks for takeoff, but "If you spill, that's on you," LOL. Warm, friendly, greeted by name, thanked...I had to pinch myself. DFW-TPA on the same trip, not a word to any passenger until about 30 minutes after takeoff. MCO-MIA no PDB but otherwise adequate service on this short leg. MIA-JFK no PDB and again no service until 30 minutes in. I do get that the 77W is a cavern with a huge J cabin, but it takes a metric eternity to get 300 Floridians on an aircraft. We could have had lunch service and a long nap before we left the gate. I was in 1A in the F cabin (sold as J on this route), and again, not a word from any FA until we were nearly over Charlotte.