What do you mean by hand memory? When I memorize I memorize bar by bar and don't go back. It taught me to memorize better. I don't even sight read anymore. I memorize and move on.
An example would be in any piece that uses octaves... if you get used to playing octaves in a piece, and you can memorize an octave passage, then in a new piece that has an octave passage, you will probably tell yourself "oh these are octaves... I remember having to play them in such and such piece" and you will read them easier. This same principal can go for pedalling, dynamics, arpeggios, whatever. If you can memorize a piece, then you are allowing yourself to memorize a huge variety of techniques (and can use them later on other pieces)... I'm going in circles saying this, but if you can't remember a day later anything that comes up in a piece, any piece that uses similar material will seem like a brand new assortment of difficulties.
I don't think that really follows to be honest. The memorising is little to do with it. It's having learned to do the technique properly that carries over. Whether you have necessarily memorised a particular passage has little to do with whether the experience carries. It's whether you've mastered the technique properly that matters. Whether I can remember specific passages or not has nothing to do with whether I'll cope with some new ones. While they are sort of related I think you're confusing memory and the more general nature of experience. There are pieces I play reliably from memory but where I don't feel I truly mastered the technique to my satisfaction. However, there are many others where I have no technical problems when working with the score but which I couldn't say I have memorised.