I'm usually careful to turn off (either with off knob or by disconnecting USB cable from my PC) external hard drives whenever I've finished using them but am still using the computer. I thought this was a good practice to extend the life of the drives, instead of leaving them running until I shutdown the PC. Sorry if this is such an obvious, basic "hard drive 101" thing to do but I just want to confirm that my thinking is right and that what I'm doing is best for the external hard drives. And not unneeded extra work I imagined I should do.