Body by Science will say once a week is enough, so as to allow the muscles to recover from their exertions. Al Kavadlo advocates three times week for body weight exercises in his Pushing the Limits book. I started off with BBS last year and it certainly worked as I consistently showed strength improvements. Being a tight git, I have moved on to pure body weight so that I don't need a gym membership or any kit at all.
Originally Posted by AdamC29
It all boils down to what exactly it is you as an individual want to achieve.
Why use a sledge hammer to crack a nut when a steam roller is even more effective, and, is fun to drive.