Why would you update a blog post after you push it out? Shouldn’t you have done the best you could the first time? Wouldn’t a new post on the matter be better?
Some good questions, and important ones. One thing I’m sure doesn’t get noticed here is I do edit my posts now and then. Some good reasons to edit your posts:
If something changes, you want the information you’re sharing with your readers completely up-to-date. Feel free to edit bad information and replace it with good information! It’s a service to your readers, especially if it’s a highly rated page.
Sometimes, what you think works, doesn’t. If you get commentors asking what you mean, fix it. Make it more clear for further readers what it is you’re talking about!
Did you find a great article or video that expands on your topic? Share it with your readers. Help them get the most out of your information by sharing more great information!
So, why not use a new post? Well, it depends on the post. If you’re not expanding significantly on the original point, it could just create two (conflicting) pages on the same information on your blog! Don’t do this to your readers if you can help it. Help them find the information they’re looking for as easily as possible.
As for the ‘do not’: Don’t edit posts to save face. Your readers will notice. If you screw up, the best way to save face is to accept it and apologize. Readers respect authenticity and even the best make mistakes.
Question for You: Have you ever gone back over your archive to update information?