It would be really great to change the duration of a transition after it was once applied.
I know, the workaround is to delete the transition and start all over again. However, a modern UI should IMHO also allow to update such things later on.
I could also imagine to do this with a filter which affects either the beginning (and the previous clip) or the end (and the following clip). Would have also the advantage of doing it in a playlist-only project.
You can also often drag the left edge of a transition too. It depends on there being additional footage in the source before the starting point, of course. You can alternate between changing the left and right edges to fine-tune it. You can also use two video tracks with overlapping clips and filters on usually the upper video.
