For people who can stay up until midnight, it allows a snipe attack if things align (like they did for me, this time). 12 hours wouldn't matter really, since I could have voted earlier in the day and then voted at 12:01 before going to bed.
It's also worth noting that you can only pull off this trick every ~48 hours, so you are getting the benefit of "double barrel" as it were, in exchange for checking out from the thread for two whole days. You can't try to get a last-minute rescue for something you're holding out for. I'd call that the inherent balance of the rule: the more you concentrate your votes, the less freedom you have. It's certainly useful to be able to spike down something you don't want. But that's, if you'll pardon the game-balance comparison, "trading flexibility for power."
And even when people
do do it, they can't add more than a single vote-down of protection to their preferred option. The most they could do is, if they're lucky, vote for two even-numbered options....but that requires that there
be two options they want to vote up, that are both even to begin with, which is effectively pure chance (and the more people who DO get it, the fewer people who can benefit from it, since down votes can't turn evens into odds or vice-versa.)
Sometimes I want to try sort of the inverse of "survivor" threads: a "grand prix" thread, as it were, where every contestant starts with (say) 10 points and needs to reach 100. You can give out +2 or -1, first to 100 wins, can't reduce things below 0 (but you must reduce something each round). Long as there's sufficient contestants (5, I believe?) the race is guaranteed to result in a winner. More importantly, though, you end up with a net
ranking of all the contestants, since no one is ever eliminated. You could even specifically go for "first/second/third place" type stuff. Gives a very different
feel compared to a "survivor," where it's a lot more cutthroat. It also removes the incentive to "spike," since you can't eliminate anything in one swell foop. (Though this
is a situation where some kind of vote cooldown--even just a few hours--could be worthwhile.)
