I believe this technique was established to prevent users from abusing the voting system and specifically for down voting, so that malicious down voters couldn't give a low down vote of say 1% then come back and give a higher down vote say 100% closer to the rewards pay-out date hence wiping any possible earnings from the creators post. I may Be wrong.
But vice versa somebody could upvote as described 10% and later improve that upvote to gain further curation rewards, IMO I believe we should all pay close attention to the value of a vote we give to users the first time, whether it be a plus or a minus and should have a no need to go back to that post and improve the vote, unless it's specifically for the purpose of gaining more rewards, which in itself I believe is wrong, but again I May Be Wrong this is only my opinion.
The fact this proposal is coming from a fairly new account as in one week old is troublesome, this is obviously written by someone that has another account which is in itself deceptive, otherwise they would have no interest in curation as they have not yet become a curator.
I understand that the rewards is what motivates most users and maximising them through curation is indeed a good thing, but it should not be a users sole purpose for being in a community or tribe, there are many other factors to take into account.
I appreciate the tag in this matter from @samsmith1971 an hope my understanding gives some relevance to your doubt, personally in either case I would not change my vote whether it be a plus or a minus.
My vote is my word if I like something I read I give it wholeheartedly once and once only, I never go back to change that to manipulate either the rewards another user can earn or my own rewards, unless of course it is for plagerizm, In that instance it doesn't matter to me what rewards I can earn, only that my vote prevents another user from abusing the integrity of the token in this case #pob