If something goes wrong during a particular folder recomputation run—for example, causing many children to be orphaned when they should not have been—it is not possible to diagnose this after the fact if a correct run intervened, since only the latest log is saved.
Without getting into the more complex machinery of RunList, it should be possible to save at least a reasonable selection of recent logs for diagnostic purposes. In particular any run which orphaned a child ought to be saved for a while, as should any run which terminated with an exception.
Whether these historical logs need to be displayed in the UI, or merely saved to disk, is another question. For the short term it is simpler to avoid UI changes.
Improvement
Major