how to do reverse fly with cable or resistance band for rear delts?

although the rear deltoid is a small muscle, we still need to train this muscle in isolation in our training programme but since this muscle is used in a lot of back exercises, we do not need to isolate them every session as well. the problem most of the time with small muscles is that we perform them too fast which is going to minimize their activation. when a muscle is small, you need to go lighter and you need to train at a slower pace compared to bigger muscles.