According to me, there should be a concept like “Differential_Full_Backup” in every Backup Technology, which will make “RESET” all the data set of “Last Differential Backup” (cumulative incremental backup).
I mean to say, after that backup, if someone takes a Normal Differential Backup (cumulative incremental), it will just take a backup of latest change (after having the 'Differential_Full_Backup') in that particular volume.
The benefit of this backup is we can run this backup (Differential_Full_Backup) in a span of certain time frame (i.e 'every weekend') with a Little High Retention Period(Product Specific) instead of a complete “Full Backup”, and after that a Fresh New 'Incremental (differential incremental) or Differential (cumulative incremental)' Backup could be possible......
Please let me correct, if my logic/concept make you feel wrong.....