When starting out with a NLP, chins are generally enough to dive progress (they might not even be needed at all - thus why power cleans are recommended). At some point upper body will need more stress to drive progress and adding LTEs becomes a solid option. If you are only training 3x per week this might pose some time constraints, but they can be worked in. It is easy to work them in if you move to a 4 day split. At your age, top priority should be reading The Barbell Prescription. It gives you lots of options for managing stress and, yes, having a light day is one such option.