external WD HD used by time machine vs HD not used by time machine.

I am using several new WD My Passport Ultras for Mac, some with Time Machine and one for general storage, e.g. not for Time Machine. On the one not used with Time Machine the Power/Activity LED is acting as the WD user manual indicates it should. After adding data to this HD the LED initially is fast flashing, indicating activity, eventually changing to slow flashing, indicating system standby, and finally to on steady, indicating idle.

On the ones used with Time Machine however the LED is always fast flashing. Obviously this is instigated by the Time Machine app (which also formats the drive to APFS (Case-sensitive) no matter how I have formatted the drive, as opposed to the non-Time Machine HD, which remains APFS not case sensitive).

Is there a way to get the HDs used by Time Machine to go to standby and then idle the way the manual indicates they should? I assume that "activity," and maybe even idle, means that the disk(s) is/are spinning. If that is so, my concern is the unnecessary wear and tear on the constantly spinning disks, which would shorten the useful life/MTBF of the Time Machine HDs.