I have been working on my lip trills across partial ... (ie second line G - 3rd space C). I have heard players do these very fast and almost effortlessly. I know that tongue placement is very important in trying to get these to move quick, I can only play them quick if my jaw moves along with my tongue.,, I am trying to minimize that but should my jaw move during this? If I move just my tongue and not jaw there isn't enough change to jump the partial. also when perform a trill from 5 line F to the G just above it do you consciously try to lip trill it a bit as the note wants to fall down the half step.