Cleaning Exabyte drives?

[Mark Plotnick]

Does the 30-days-or-30-GB rule apply to drives in which the tape is ALWAYS
left loaded?  We reserve one drive on each fileserver for dumps; the tapes
are always loaded, and the dumps are started automatically a couple times
a day (by cron).  I fear this practice does a much better job of
magnetizing and depositing oxide on the head.

The funny thing is, we didn't really start to see the "tape may be wearing
out or the head may need cleaning" messages until after we started using
the cleaning cartridge.