There is a reason that most of the most successful programs are what they are these days.  We are moving more and more away from muscle isolation exercises and into multi-joint, multi-planar movements.  Instead of things like bicep curls, we are rowing and pulling.  Instead of leg extensions, we are squatting, lunging and deadlifting.  These types of exercises provide SO much more benefit.  So much more bang for the buck.  The basic rule of the body is that the more muscles, systems and directions that you can use, the more benefit you will get.  More hormonal interaction.  More neural activation.  More calories burned, more weight lost, more muscle gained.  Isolation exercises originated with bodybuilders.  They became our first generation of personal trainers, because they were the only ones in the gym before that.  Therefore, not to knock, but they taught what they knew.  There is an old saying that goes “Do the best with what you have.  But when you learn better, do better.”  The fitness industry has fought that for years.  We are learning better, but people are still stubbornly hanging on to what is comfortable, because it’s what they know.  Don’t be that guy (girl).  You are learning better.  So therefore, do better.  Your body will thank you.  Not only in the long run, but in the short run, as well.