I've read some threads on other hardware forums in regard to hard drives demagnetizing due to non-use. Has anyone experienced this? I tried doing a Google search but cannot find anything related to this, only using
demagnetizing as a way to wipe a hard drive. I've had hard drives sit in a dresser drawer for more than a year and did not have any problems using them as spares, no sectors were damaged.

You're asking what is the stability of magnetic media over time, and there's no real answer. Not using a HDD does not make it less stable, but sectors can go bad over time just like they would if it was in use.

Older hard drives with stepper motors and true low level reformatting could possibly suffer a fade or tolerance shift, but could be reformatted.

With modern drives, the media is more optimized, the tracking is servo controlled and compensates for any drift.

It seems that modern drives are less likely to deteriorate when out of use, unless stored in adverse conditions of temperature or humidity - remember drives are NOT SEALED, and temperature or pressure changes result in air passing through the breather filter.

Yesterday, I put a 2gb hard drive into my machine yesterday (to wipe it before throwing it in the trash) that last saw a power connector sometime back in 1997. All of the files were intact. I would think longevity would be determined by the environmental conditions in which the device is stored.

I also have a set of Red Alert CDs from back in 1995 that are still completely viable.

Consumer drives the heads and the platters can go bad, no only with long term storage. All else should be ok such as the motor, which is sealed and shouldn't cause a problem. Unless you chose a seagate drive, many seagates 500gb> have motor problems sooner or later. Many have them from new, on first use they can squeak like a young bird.

I do remember the mfs blurb that they could be used for storage. Shame they didn't say long term storage, as they do for the enterprise drives.