Home server with a bunch of 2 TB drives in raid 5. And 2 workstations with a whole lot of internal and external drives. And some older machines and 2 laptops. In total about 60 TB, but half of it is used as backup.
When I need a new external drive I buy 2 of the same model, one to use and one for backup. Backup drives are usually not connected only when needed. Some of them have been in the closet for months while others are used weekly. Unfortunately it never takes very long for a hard drive to become full, no matter the size
Once full and mostly used to read from the backup unit won't see daylight for a long time (hopefully).
The drives in the server run 24/7 and they fail more often then the external drives with auto sleep function. Seems keeping your drive running means be prepared to buy new ones sooner. But my home server also hosts websites so no option to shut it down or put it in sleep mode.