I don't claim to know everything about this workout shyt, but when I started adding pull-ups to my routine it gave me some of the most notable gains of any exercise. It's a compound exercise too.
It engages too many muscle groups not to be a valuable exercise. Some people choose lat pull downs, some people do rows. My poison has been pull-ups. To say it's only for beginners is misguided. It engages so many muscles in your back and biceps, it improves overall strength, and helps prevent back problems.
Add 3 or 4 sets of 10 to your routine, take before and after pics, you'll see a noticeable difference in 30 days.