tl;dr is there a threshold on data copying where it becomes harmful for your hardware? Hardware in question is a ~4yo WD My Passport 4TB, and a brand new Seagate Desktop 8TB.

How would you backup:
>500 gigs from an internal drive to an external
>2TB from an internal drive to an external
>cloning a 4TB external to another 4TB external drive
without stressing your hardware too much? I see three basic options:

>1. Do it in one go
>2. Split the copying over a couple of days but keep your drive plugged in
>3. Split the copying over a couple of days, unplugging it after each use