If you are changing a layer's duration (Time Stretch or Time Remap), Frame
Blending will aid the transition between frames by taking information from
previous/next frames. This creates smoother "looking" playback.
A nice trick I use from time to time : Time stretch a layer to 200% with
frame blending, precompose, then time stretch back to the original duration.
You end up with a clip that runs at the expected frame rate but has a
ghostly blending through all the frames. Repeat the step for more
application of the same effect. It looks good for openings to industrial
jobs. The good ol' financial inudustry clips (stock ticker, coins falling,
cash register opening) all composited with this frame-blend misuse creates a
great smooth looking opener.
Eno