These two partner assisted pull-ups are a great option to ensure full-range of motion and individually based assistance.
Most lifters struggle with finishing the movement by getting their chin over the bar. Although many use bands for assistance, a band won't help you where you need help the most: at the top. Also, partner assisted pull-ups allows the person that's assisting to dictate how much help is needed.
If you're a true musclehead like I am, you've probably read (or heard) a lot about periodization, either from classic textbooks by East-European sports training and weightlifting authorities (including the classic texts by Tudor Bompa), or by researching the subject online.