I find it a bit strange, that Stack Overflow is that restrictive at times and locks up/downvotes after some minutes have passed.
Why is there a need to lock votes at all? Isn't it potentially contra productive?
I today found an answer of how to check if string values are only using the English character set. I found one answer good & simple and tried to use it, so I upvoted. During testing however, I recognized, that it was not working correctly, because important characters like even space were not recognized as English characters. So I thought it was not justified to upvote the answer to make it more attractive to other people, who see the answer, but I simply couldn't correct it.
Can you tell me, what would have been wrong, taking back my upvote, or even downvoting this answer again?
Possible Result of locking votes too early
Probably there are plenty of answers, that look appealing at first, because they are simple and are getting upvoted because of this frequently, but once the users recognize the answer is wrong, they can't correct it anymore.
That is, the most competent votes (the ones of actual testers) are potentially blocked this way.
Summary and final plea
To come back to my initial question, why it is needed at all to lock votes. I read the arguments here and partially it makes sense to try to get the people to be more thoughtful about what they upvote, but I wonder how many users of Stack Overflow are active that frequently that this really has a big impact. I mean, if most of the users are only reading answers and maybe posting questions every now and then (as I did until not so long ago), then most of the votes will not be done as thoroughly, as we might wish and so I fear, what I described above will have a big impact (that answers that appear simple, but forget half of the job) are upvoted.
I would appreciate, if locking of votes would be abandoned or at least, that the period in which votes can be changed, would be made much longer, so users have a fair chance to chance their votes after testing (say 3 days at least, so also weekends are no problem). Once again, many of the SO users probably see a possible answer, give their thank-yous, upvotes and probably will not return to SO for the same question, if the answer they got from SO solves their problem. That's what you should think of when choosing the period in which a vote can be changed.
BTW. I think the post I used as an example is not that bad. It doesn't really harm someone, but you know, if it wouldn't already have about 10 upvotes, I also wouldn't have considered it to be a valid and highly appreciated answer and would probably have been led to the right one immediately.