Steve Gibson still advocates never turning of spinning disks in this modern era.
One of the quickest ways to kill a HDD or fan is to make it spin up its motor from idle frequently as a consequence of power saving policies.
Personally, I never turn my computers off unless I know I won't be using them for extended periods of time (say a week or two). The power bill savings aren't worth the decreased hardware life.
For consumer usage I find this hard to believe. I only use my laptop/desktop's spinning disks like 2h a day at most. Then there are hybrid disks or systems that are likely sleeping the disks when use is infrequent.
I have a ~12 year old (110,651 power on hours), 500GB PATA Maxtor/Seagate HDD with 135 power cycles.
It's still alive and kicking ass as we speak.
(( Why do I have these? Well, because they're SCSI or SCSI II, which the hosts support. And because I've not bothered to replace the drives with solid-state hacks that put SD cards on the same interface. ))
Sure, the main problem was the subpar PSUs, but are you sure what your PSU is enough?
It might even be the case that, if you bought a replacement six years ago and kept that powered on 24/7, you would have ended up paying less in (hardware+power).
Besides, it's not this hard drive anyway. At this point I want to see how long this wizard of a hard drive will keep running.
With modern power management there’s less of a reason to power it off. S3 can power down most peripherals when they aren’t being used and draw just a few watts.
Even when shut down, the PSU still needs to consume power so it can turn on when you press the power button, keep the internal clock running, and a few other things. It’s minimal draw but it’s still using electricity. Only way to completely turn it off is by switching off the PSU (if you can) or unplugging completely.
That's the job of the mobo battery, the PSU just charges it as an afterthought.
And the failure rate of drives with an agressive powersaving[0] says there are some truth to it.
[0] WD Green, remembrr them?