Currently, your votes are locked in permanently, after a 5 minute window from the time of your first vote, or your first vote cast after the most recent edit to the post (https://meta.stackexchange.com/a/5213/278437).
Rationale for the status quo:
- Vote locking combats a tactical voting scheme, where a user downvotes another competing answer (or several competing answers) so that his answer "gets ahead" and gains more exposure as a result, then retracts the downvote (https://meta.stackexchange.com/a/18046/278437).
- Vote locking prevents a person from going back and undoing a large number of upvotes, causing a large drop in reputation for many users or a particular targeted user (https://meta.stackexchange.com/a/80763/278437).
- Jeff Atwood suggests that there are several other (unnamed) "exploits" based on undoing votes (https://meta.stackexchange.com/a/18374/278437).
Vote locking directly hinders a completely legitimate use-case: correcting mistakes.
For example, consider the case where an answer appears to be helpful at first and you give it an upvote. Later, however, you realize the answer was wrong, or you misunderstood the question originally, or another user's comment or answer changes your mind, or it's years later and you're simply older and wiser, but now you can't change your vote anymore. (Or, the similar situation where you give a downvote at first but need to change it later.)
By allowing small exceptions, the staff acknowledges that changing your vote has legitimate use cases and that vote locking has real costs for user experience. The 5 minute limit is intended to mitigate these problems, but vote locking is still far too restrictive and inflexible. You can take far longer than 5 minutes to correct your mistakes or change your mind.
Just like asking, answering, editing, commenting, voting, accepting, deleting, flagging, reviewing, and just about every legitimate action on the site (see The Complete Rate-Limiting Guide), changing your vote on a post should be rate-limited, not prohibited.
Appropriate rate limits can be set at several levels of granularity, including:
- A limited rate for changing your vote on a specific post
- A limited rate for changing your vote on answers to a specific question
- A limited rate for changing your votes site-wide
Appropriate and reasonable limits should be set to prevent known or anticipated abuse schemes, while balancing this need with the impact on user experience. Rate limits can solve the problems that vote locking is meant to address, without blocking the legitimate use-case.
The current rate limit, zero, is unacceptably low.