In current version, the timeline shows colored sections for the changes to happen in a specific box. It should show the changes to happen in general.
In general, the timeline should be always available.
In specific, especially when we use overflow. Cf the video that I attached:
there are changing about to happen on a block because of an overflow event, but this one is not visualized in the timeline.
My gutt feeling telling it would be simpler to fetch all the events for all the scheduled block, always. UX would be better.