Have some idle time at work, looking to see if anyone else is similarly bored...
Take two identical twins. One does no other exercises except direct biceps exercises, ie various versions of curls. He focuses on feeling the biceps doing the work and on progressive overload.
The other twin trains his upper back with compound exercises and occasionally throws in a set or two of curls as an afterthought. He focuses on progressive overload.
Who will have bigger biceps after a year? Does the answer depend if the twins are beginners, intermediates, or advanced trainees?
Similarly, take three triplets. One does 100% of his chest training with compound exercises, one does 50% compound exercises, 50% isolation exercises for his chest, and the third does 100% isolation exercises for his chest. Compound exercises are performed with progressive overload as the objective, isolation exercises are performed with feeling the muscle work and progressive overload as the objectives. Who will have the biggest pecs (not tris, shoulders, etc.) at the end of the year, who will have the smallest?