This question already has an answer here:
Sometimes, you ask a question and you are lucky enough to get an answer in one or two minutes. I don't understand why I have to wait for 15 minutes before I can accept the answer if it solves my problem. To be honest, the most annoying part about this is having to keep an extra tab open in my browser for 15 minutes until I can accept it.
Now, according to Jeff's reasoning, "they're accepting the first answer that comes along without considering all their options."
This is not always true. Now, on a website such as stackoverflow (I'm only posting it on the stackoverflow meta because meta.stackexchange redirects here so I'm assuming it's the "general" meta) there is a good reason for this timer. However, on a website such as superuser, where a lot of problems are of broken things, if people offer a solution that fixes their issue, there's no point in waiting 15 minutes, their problem has been fixed and their question has been answered.