Rather than select no overwrite protection (which means that sooner or later, you WILL overwrite a tape that you wanted to keep. I'd set the OPP (Overwrite Protection Period) of the media set such that when the tape is due to be reused, it is available for overwrite
For tapes reused the same day each week, use 6 days
For tapes reused the same day every other week use 13 days, etc