Allow me to change my vote if I discover an answer is wrong after I upvote it
A few times I see an answer that upon reading seems to be exactly what I want -- the perfect solution to a problem. I think wonderful my problem's solved and upvote it. A half-hour/hour/day later after I've tried implementing their solution, I come across a roadblock -- their solution fundamentally won't work and could never work; e.g., they tried to do some sort of action not allowed by the web framework.
Not only did their solution not help; it wasted a lot of my time implementing something that could never work. And now the next person who comes along will see their solution and try to implement it and will see that its upvoted. Maybe, I'll write a comment; but maybe they'll miss it or decide they need to try it themselves (hey it has a few upvotes -- it must have worked for some people, right?).
Now, if I have enough reputation I can trivially edit their question and then be allowed to change my vote; but to me that seems like cheating the system in an unintended way.
I think a better method would be to unlock the votes if you leave a comment. Or have the vote message say, your vote is locked until you leave a comment saying "Changing vote" followed by a reason (or had -1/+1 that is opposite your original vote; then you are allowed to change your vote to that).
I know this is similar to other requests: Isn't the "vote too old to be changed" a little too eager?
but I think that having vote locking is a good feature; just maybe relax it following a user leaving a comment in a way similar to how its relaxed after the answer is edited.
Otherwise, I think I'm going to have to seriously cut back on voting.