Started doing the opposite one - adduction - just 3 weeks ago. Directly after I squat, when my hips and legs are still sort of fried. It's not one of those exercises that's good to pile the weights on, so I keep it at the usual high rep count, and try to maintain good control and time under tension. I don't know how I'll feel about them in the long run, but for now they do a good job of finishing off the strength reserves in my legs and gives me a breather before I move on to other stuff.