It happens that the selection is much larger than the data range. In such case, the timeline looks a bit strange due to very tiny buckets. This is because the bucket size is based on the data range instead of the selection.
The improvement could be one of those solutions:
set the bucket size based on the selection range
set the selection span on the data range
The first presents the advantage of staying coherent with the user's choice.
sylvaingaudan
commented
2 years ago 
It happens that the selection is much larger than the data range. In such case, the timeline looks a bit strange due to very tiny buckets. This is because the bucket size is based on the data range instead of the selection. The improvement could be one of those solutions: