I don't think you should close your questions lightly. There are very few questions that have a definite answer that will never change, or that cannot be improved upon.
Someone might come in three months or a year, or later, and be aware of a caveat that nobody knew about when you posted the question. Maybe there was a security flaw in the approach and it was discovered later. Maybe it doesn't work anymore because Windows 20xx doesn't support feature Y anymore. Maybe the question was about Internet Explorer 10 and the correct answer changes for Internet Explorer 11. Maybe you asked the question in regards to FireFox, Opera, Internet Explorer, and Safari, but the answer doesn't work in the as-yet-unreleased super-duper-browser that will dominate the market in 3 years.
The way I look at it, these questions and answers are not just for you but for anybody who might have the same question in the future. Just because an answer works for you now, it doesn't mean necessarily it will work for someone else in the future.
By letting the question open, you give the chance for other people to contribute an even better answer later.
Reason for closing a question:
- The question has attracted noise/trolling/attacks or other bad behavior.
- The question has been asked before in a different post which has a better answer (then, post a note with a link to the other alternative and close it).
- The answer will truly not change (for example, because it's linked to legacy technology that won't ever be updated)
Reasons why I might be completely wrong about this:
- If no one ever closes the question, who's going to stop people from trashing the question in a year?
- Editing power allows for highly trusted users to modify an answer when needed, as new information becomes updated, so leaving it open might not be necessary.
The need for guidance on closing posts has partially been provided by the reason for closing which must now be selected. "Already has the best answer" isn't on the list at all. In general, it is a good practice to only close a post for one of the provided reasons.