The Wikipedia article http://en.wikipedia.org/wiki/Linear_Tape-Open lists some interesting technical data about LTO tapes that we would like to comment on:

Tape durability

An LTO tape is good for

• 15 to 30 years archival (this number is probably assuming the tape is not read)
• 5000 cartridge loads/unloads
• Approximately 260 full file passes. (One file pass is equal to writing enough data to fill an entire tape.)

Namely the latter value then results in the life time (for an LTO4 tape): 

• one entire tape written per month: 17 years
• one entire tape written per week:  4 years

These values reflect in general our own experiences with LTO tapes. However the values strongly depend on the tape usage.

One sentence is interesting namely for those who run PresSTORE's Verify after Archiving on LTO tapes:

LTO uses an automatic verify-after-write technology to immediately check the data as it is being written, but some backupsystems explicitly perform a completely separate tape reading operation to verify the tape was written correctly. This separate verify operation doubles the number of end-to-end passes for each scheduled backup, and reduces the tape life by half.