If two cuts have no more than 16 groups each then it is possible to combine the two into one cut with no more than 256 groups. And if the two constituent cuts are each "good" on one channel, then the combined cut will likely have many fewer groups than the maximum possible (e.g. for 8 and 12 you might get 20 in the joint cut rather than 8 x 12 = 96).
If two cuts have no more than 16 groups each then it is possible to combine the two into one cut with no more than 256 groups. And if the two constituent cuts are each "good" on one channel, then the combined cut will likely have many fewer groups than the maximum possible (e.g. for 8 and 12 you might get 20 in the joint cut rather than 8 x 12 = 96).