The interactions/keyframe/timeline would benefit hugely from an update.

Problem:

Adjusting the positions of literally hundreds of instructions is extremely time consuming. Especially if all you wanted to do was add some extra time at the top that then has a cascading issue. This makes it super tricky to adjust timings of the feel of a website as it scrolls.

Solution:
Ability to group keyframes and set the amount of percentage that group takes up (by input or by dragging the top or bottom of a group container) would really help. Imagine the groups took up vertical space and could be clicked into to reveal their animations within their allocated space.

Grouping could be an added right click option after selecting multiple keyframe instructions.

Grouping would also present possible extending options such as having alternate groups for varying devices in the same list. This in not possible at present without having to allocate an entirely new list or adjusted duplicate.

Hope that helps should this idea be reviewed. :)

Cheers
Hamish
UI designer