Best practices with external HDD chassis

Simple question: I just got a good external HDD chassis that houses the C: drive from my old PC and hooks into my new DS PC via a USB 3.0 connection. I just noticed that it does not power down when the PC is switched off. From the small sound it makes, it seems that the HDD inside the chassis is still spinning. There is an on/off switch at the back; should I get into the habit of switching this little box off and not powering it up again unless I need to access the drive, then switch it off again afterwards? When I power my PC down, should I always switch the external box off too? Or should "always on" be the healthiest way to operate? Thanks!

Many thanks. Removing the data then formatting the drive before putting the data back is a very smart way to save space and minimize the risk of a crash. However, I'm still not sure whether to keep the drive running, or use "off" as the default mode and only switch it on when I need to access it.

I mean, it's just personal preference at that point. I personally leave my HDD's on as I don't like turning them on and off, on and off.

In the IT world, there's two sides of belief's when it comes to mechanical hard drives.

One side believes the theory that HDD's are like engines. And the most harsh time for an engine is the initial turning on. Same for HDD's, that jolt to get them going just degrades their life span.

I believe that side. Which is why I tell people, recommend wise, and do so myself on leaving your PC on and just restarting/turning it off like once a week.

Other side... no harm no foul. Turn them on and off all you want.

Really though, there is no best proven practice. You do what you want here really. There is no proven wrong or right way. Just us nerds with our own set way of doing things. If there was a legitimate proven published written recommendation with proof to back it, I'd gladly give it to you. Just do whatever you want here. Leave it off and only turn it on when you need the data if it makes life easier.