if back is made from almost 13 different muscles and some movements involve more the lats (pulldownz for example) while others involve more the "upper back" and if a muscle cannot change his shape (well, if not under surgery) why all we speak about "back width" and "back thickness"??????
it would be more correct to speak about "upper back" ,lats and lower back.
example one; boy A does heavy pulldowns,no rows,no deads and no trap shrugs.
results; "wide" lats,weak upper back,weak lower back.
example two; boy B does heavy PDs plus heavy deads.
results; "wide" lats plus "thicker" low back and traps.
example trhee; boy C just do heavy deads.
results (if he gets not very good lat genetic): strong lower back,strong traps,so so upper back.
I think that we should speak of (upper,middle and lower) back development instead of " back width" and "back thickeneSS" because the essence of the juice is that if lats are well build they are wide and erectors are thick because of their shape