For example, if I have pose A and pose B, I can insert a breakdown pose between them.
If the slider is -100%, it'd be equal to pose A. If it's 100% it'd be same as pose B. Any value in-between just blends between the poses.
(I think that in Blender you can even go like 120%, so it actually overshoots the values for each parameter)
For those who likes to block characters with stepped keyframes, it's a must have.
Is this something feasible to implement in After Effects? I have no idea of its limitations under the hood.
Cheers!