Hey CT, hopefully this question makes sense to you.
Obviously, if someones goal is to get as big/muscular as possible isolation work should be required, especially for a bodybuilder. However, do you feel it would be necessary for someone not looking to add to much over all weight? If the trainees goal is to be 5’10 165-170 lbs lean athletic look would his time be better spent focusing on getting stronger on compound movements.
At that body weight how much added muscle can tricep extensions, bicep curls, or laterals add that heavy pressing/pulling will not?