An excellent point and question. My understanding is as of at least LTO-4, tapes have an on-board RFID chip that holds the tape's read/write history, maybe 1-2 other things. Every time it's used by a drive some data gets written to it, and I believe that's where the tape notifies the drive "hey I'm done, no more." Perhaps you guys could investigate pulling that data to help discern end of life? For me I'm looking more toward end of a given tape's life, rather than a human decision of "I've written to it 200 times, so I'd better go ahead and replace it," if that makes sense.
Veeam B&R v9
Dell TL2000 via PE430 (SAS)