There's no reason to be saving up your votes. Granted, particle makes a good point. Don't vote for the sake of voting. Vote because the node struck you as good or bad.
in reply to on wasted votes ...
If the reason you're saving your votes is in case you're waiting for a really good node, don't fret too much. First off, you can only vote on it once, and unless there is a really long discussion spawned, you're not going to use up that many votes. Especially considering that you've got a few to spare.
Secondly, even if you did run out of votes, if you think the node deserves it, add the node to your nodelet and come back to it the next day. You'll have a fresh supply of juicy votes to share tomorrow.