That works, the key I think for lip-synch is the start of the spoken words match. You can remove frames in a pre-comp (if this is AE) making sure you don’t create jump cuts (e.g. cutting 2 frames of mouth close with frame before and after cut with mouth also closed). Also if you work by animating Twixtor Frame Num param, like at frame 75, you set KF for frame num to 75 and at frame 78 you set KF 76 sort of things.
Pierre