The proposed feature could be like:
Select a time frame, Right Click, choose "Preserve screenshots".
And the screenshots within this time frame will not be automatically deleted.

The reason I want this feature is because screenshots may provider more help other than logging times. Take the motive of this PR as an example. I had a research on one problem in our system recently and had some progress. However, the clues are still not enough to solve the problem, and the chance this problem occurs would be very rare so other works take advance of it, which may last several weeks before I can work on this problem.
If at the time I return to this problem, all the screenshots when I research on this problem are still available, they could provide great help for solving it.