[nritchie]

An encrypyted drive is likely to have (close to) equal numbers of 0's and 1's full or empty so any of these arguments are moot.

[theandrewbailey]

If the drive isn't encrypted, is it possible that controllers use some kind of encoding to balance out the number of bits, so that there's not a long run of 0s or 1s?

[userbinator]

Yes, this is necessary for high density NAND flash and is referred to as "whitening" or "scrambling". Not needed at all for SLC or older MLC.