In 1979, I started doing Nautilus workouts using machines. Key to these workouts was a timing ratio of 1 to 4 of the positive to negative part of the repetition. And there was a trainer who was with customers that assisted with forced reps and applied more force on the eccentric motion as one approached failure. We only did one set per machine and did no more than 8 machines per session. It was a very efficient gym workout.
I liked the workouts a lot and I was in great shape.