@loren like someone else said it depends on the style of drive. Older drives are cheap now but have more moving parts & so fail more readily but may be like, the usb external drive for music ur friend built u. Theyre heavier too.
But if its the tiny ram stick sized new solid state drives those things are great for not needing to maintain and just Working, tho they get hotter than old drives for sure. So if a ssd is acting funky its more likely heat issues than a defrag issue id think
@loren It depends. SSDs don't really benefit from it. An HDD with a Windows format like FAT or NTFS will still benefit a lot; an HDD with a *nix filesystem like EXT4 or BTRFS will still benefit from it, but maybe a bit less than a Windows drive would.