Disk Spin Down power management settings

I ran my NV+ 24/365 for three years and put over 25,000 power on hours on the original 500GB disk. I had the second 500GB disk fail within the first month, but the replacement (same make and model) also ran for over 25,000 hours. Those two disks and two others I used to expand the volume are in other uses, one is the system drive on this PC. The drives were replaced with larger 1TB drives because I was running out of space. My primary NVX runs 24/7 and the backup uses disk spin down. Each unit has 2x3TB and 2x1TB drives, and one of the 1TB drives has over 16,000 hours. I have actually lost more drives in the one with disk spin down (2) than I have in the one that runs 24/7 (1).

Professionals have been arguing for decades whether it is better to leave the computer on and the drives spinning 24/7 or shut them down every night and deal with the wear and tear of the start up and shut down routines. Electricians have been arguing over whether it is better to leave fluorescent lights on 24/7 or turn them on and off, with some tests leaning towards leaving them on.