Isn't the reason for the seven day window also to prevent delegating one's HP to several different accounts to be able to self-upvote own posts several times?

By the way, I think we should reconsider the five minutes curation window (directly after a post was written), because it clearly disadvantages manual curators who try to read and evaluate posts before they decide to upvote them or not. Until they have done that always lots of automatic upvotes have already come in. Also it makes 'curators' lazy (especially since there is 50 % curation reward): they simply upvote the same people again and again, while not enough users are seeking for new authors (respectively honor posts from old authors who aren't on their 'lists').

I see no reason to be rewarded less for a late manual upvote than for an early automated upvote.

Considering the high percentage of automated upvotes, I think it's simply a myth that manual curators find 'quality content' early, and then more upvotes follow and reward them.

I wrote two posts about that problem:

Here and here.