A to B 1
A to C 2
則，為符合等比例原則：
B to A 100
C to A 200
若
A to B 1 B to A 100
A to C 2 C to A 30
則
流動失衡
導致
A to B 1 B to A 15
A to C 2 C to A 30
A需維持空間規則
否則A的生產線會崩潰