I read a year or two ago people were buying used hard drives in bulk and stress testing them in something like a 40% failure rate and keeping the 60%, so basically buying 10 hard drives to get six. Does someone have information on this?

I have been using an 8 tb external for my home lab for a year and a half now and am wanting to expand. I have been thinking of getting a usb c/3.1 hard drive rack and just buying a pallet of 20 4 tb used hard drives and stress testing all of them until i get a solid 10 or so that dont fair under stress testing. Does anyone have a solution? I was thinking e waste recycling plants or amazon liquidation warehouses but I don't know where to start. Thank you.