Hmmmm.... this would be a similar idea to how collecting miles works with airplane companies. You collect the miles, but if you don't spend them until a certain deadline, they become invalid.

I think most of us agrees that this would a feature which we don't need, but some of us *could* use occasionally; for instance in the rare cases where I have spent my share of daily votes, and then suddenly discover a node I really like a lot, and which I would honour for this (for instance if someone took the time to answer my question in SoPW). In this case, I really would be ashamed not giving a + vote as reward; but - BUT (very big BUT): Every node has an ID, and if I like a node so much that I don't want to leave it unvoted, nothing keeps me from bookmarking the node and cast my vote the next day. Admittedly, this is a bit inconvenient, but if I value a node high, I will accept this invonvenience, and after all, this doesn't happen so often.

So I would prefer sticking with the current scheme.