More careful is actually a stupid advice. People make mistakes, it's unavoidable. GH makes mistakes easy to correct, which is how it should be.
There are bots out there that scrape sensitive information from Github repositories. If you inadvertently push up a commit with a secret in it, then consider it compromised. Email is no different in that regard.
If, ten seconds after I've clicked Submit, I discover an embarrassing error in the code, or that I've accidentally committed some personal information, or I've sent the e-mail from the wrong address, or anything else I haven't thought of yet, there's nothing I can do and it's public forever.
Some would see this as an anti-feature, but I really do like using GitHub because I have the ability to go back and edit or delete my Pull Request if I spot an embarrassing mistake. I know the solution to this is "be more careful", but I still feel anxious sending e-mails to a mailing list, and calm using GitHub.
Does anyone relate?