your fighting weight if you are a beginner, the weight of the bag should be limited by what your wrist and other joints and knuckles involved in striking can handle, so you can hit loosely and are not afraid to damage something
I never thought of the fighting weight analogy. I like it! Anything upwards of 50-60kg I have used and had benefit from. The heavier the better though, why not!
You need different size bags to accomplish different things. Imagine workng on nice, heavy combinations on a heavy and immobile bag. Now try those on a light bag that moves around all over the place which you have to keep ad******g for with foot movement. Totally different workout.
