I only 256gigs in my desktop, which is usually 40-70% full. It goes up and down based on Steam sales. I play then uninstall to free up space.
I also have 2TB on my file server which I try to keep at half because keeping it all backed up is a hassle. My offsite backup server has 2Tb to match, but due to how long it takes, I only backup critical items offsite, the rest is done locally on a smaller external drive.
watch out for those external bays, they trap heat which kills off the control board chips early.
The mechanical parts of the drives rarely fail, it's the electronics that die either due to defect, or accelerated wear from heat stress.
You should look into the months long
Google drive study. Here is a more readable version, and
here is a summary for the lazy ones. They studied all of their drives for a while, all different makes and models and found heat was FAR less a factor except when the drives reached an age of 3-4 years
and spending 50% of their time above 40C.
"One of our key findings has been the lack of a consistent pattern of higher failure rates for higher temperature drives or for those drives at higher utilization levels."
In this paper they said they didn't have the technology to test for vibration, and didn't want to give a drive recommendation for which they felt was best so as not to skew the information they had collected. However, in another version of this (or an interview, I forget), they concluded vibration was an issue and arrived at that because the drive they found to be much more reliable was the one that had both ends of the spindle supported (Samsung or Hitachi). All others were relatively similar in reliability, except those.
This is also pretty interesting,
these guys show what vibration generated by simply yelling at your computer does to a drive. If yelling does that, imagine what real vibration or a bump does to it.
My own experience mirrors Google's.
If and when SMART does find anything out of the norm, the drive has little time left, no matter how minor it is. In over a third of their failures, the drives showed no prior signs of problems at all. Considering how many drives I replace in laptops vs desktops, I also have drawn the conclusion that vibration is the death sentence. I have seen drives bake in both and thrive for years, but show me a laptop with a dead drive, and I bet you will find it missing the rubberized feet, and signs of hard living.
I also agree with Davkol, never buy from the same batch if you can help it.
They are all the same, same transport and living conditions, same electronics, etc... They tend to fail relatively close to each other because of it. Companies setting up new servers order boxes of drives from around the country (or world), then mix and match, just to avoid that. It's painful watching a raid fail and as you rebuild it another drops, then another... I've seen 6 drives swapped out on a 8 disk array within 6 hours of each other, the data was safe, but the owners wallet sure wasn't. We survived the night with only 1 drive to spare and had to overnight a bunch of new 10k drives. Unfortunately, the replacements were all one batch and so were the overnighted drives, so you can guess what happened. Unfortunately this was systemic of the incompetence there, so I didn't stay long.