Hence the importance of distributing your coins across several addresses and discarding an address after the first transaction
Not reusing an address? Sure.
Discarding an address? Nope.
I still have copies of every private key for every address I've ever used, even ones which I used once years ago and have never and will never use again. Why discard them? The files/back ups already exist so it takes no effort on my part to keep them, and there is always the chance that I accidentally reuse an address or a third party accidentally pays me to an old address, at which point those coins would be lost forever had I discarded those keys.
In the words of Satoshi:
Sigh... why delete a wallet instead of moving it aside and keeping the old copy just in case? You should never delete a wallet.