Muscle Priority Training Principle
We have all seen bodybuilders hanging a huge pair of 20 inch guns through a torn off T-shirt or a vest who has 10 inch calves and legs that look like toothpicks. Bodybuilders who only train for size without any consideration for symmetry and balance will never feature in any bodybuilding competition.
Put that big guy with the huge arms in a pair of posing trunks and put him onstage, he will look like a beginner who got lost in the arm section of his gym. It looks ridiculous because his/her body is not balanced and shows no refined symmetry.
Muscle priority training can be easily applied just by looking at yourself in a full length mirror. The weaknesses will easily show themselves, if you have ever been to a bodybuilding show you will know exactly what the judges are looking for. Depth, proportion and symmetry are the basis on which all bodybuilders are judged.
It has very little to do with actual size. Mr. Olympia Mohamed Makkaway stood only 5'3" but his arms looked like they were 25 inches. His perfectly balanced physique was not judged by the actual size of the muscles, the judges don't carry tape measures, they are concerned with the illusion of perfection.
With this in mind one can effectively use muscle priority training to concentrate on your weak body-parts. For example, let's assume that you genetically, just like your father, have an under-developed upper chest. You would then start each chest workout doing incline bench-press or D/B press.
If you feel that your shoulders are weaker than the rest of your physical development you would still start your shoulder with a compound movement like military press but you would then go directly to rear deltoids. The more strength you will have in your rear deltoids the greater the weight you will be able to lift doing a movement like military press.
Muscle group priority can be very effectively used to build up a weak body-part by starting your workout hard and heavy at the muscle group you're weakest on. You should never think of the body-parts that are gaining muscle to be surging ahead, but rather look at your lagging body-parts as needing to catch up.