It would be great if a certain period on the timeline could e selected and consequently removed, extended or moved to other places on the timeline including the possibility to create transitions that allow for smooth linkage of the new animation pieces. I think so far this is not possible.
On my recent project I decided also to produce a shorter version and to remove certain parts of the animation. As this was a one shot animation I was interested in smooth transitions between the remaining pieces. I achieved this with a combined workflow of CA and After Effects, but it would have been great for the animated character to do this in CA.
Here is the example; longer version: https://youtu.be/85tSQY9K-MY
shorter version: https://youtu.be/rms8csKkdSQ