I have seen some good replies here but some things that I want to point out are that how often you post on the social media website will partly depend on what you are posting, who your followers are, what you are trying to achieve and some other things that vary from situation to situation.
I would recommend trying to post daily if you can and if not then at the very minimum, every other day. A couple of posts per day would be better but I understand that time matters.
One thing you don't want to ever do is post junk or low-quality posts just for the sake of posting something as that can cost you followers.