Updated: Apr 13, 2019
Many guys in the gym train too much of the mirror muscles, which includes the chest, arms and many other muscles that can be seen by one in front of a mirror. This can create imbalance and can sabotage posture. The back muscles is another huge muscle group and can surprisingly provide a complete aesthetics - it makes the chest look wider and bigger. It is also important to train the back muscles to have a fulfilling body strength.
The back has two areas: the lower and the upper back. The upper back and the lower back. The lower back usually gets a workout during squats and deadlifts. Meanwhile, the upper back is composed of the mid-back (trapezius, rhomboids, etc) and the side (lats, etc).
The two main aesthetic qualities of the back are the width and the thickness. For the width, the exercises are targeting mainly the side or the lats. The exercise for this are lat pulldown, pullups or chin ups, deadlifts, modified rows, etc. On the other hand, the thickness of the back targets the mid area. The exercise included for this are rows.
According to my friend who's a body builder, pull-ups can be done everyday as the back can recover quick. This may be true but not all has the same body type. I find, however, that I can do back workout multiple days in a week.