I've seen studies like this. Technically correct. However, it can get very boring just using the same exercises with no variety. I use basic free weight movements like squats, rows, sometimes rack deads, seated overhead presses, but also have several nautilus machines, double chest, lateral raise, pulldown, multi exercise, leg curl,leg ext- though my ex gf broke that, and universal pullover, also needs a cable replaced, vertical leg press, as well as a couple of dumbells for variety. i tend to go with these, do chins, dips and calf raises on multi exercise machine, and can do a lot more if the whim hits me. Makes it more fun and motivating.