To follow through on the "Use Heavy Weights to Gain Muscle" principle you must train accordingly.
This article was written to give you an insight on your weight training exercise choices: isolation or compound? Isolation exercises aim a specific muscle, dumbbell flies or preacher curls for example.
The problem with this type of training is it is too specific, requiring little if any help from your other muscles.
These exercises are not suited for massive muscle gains especially since they do not get your intensity levels up to raise testosterone and increase your metabolism as much as compound training.
There are however good reasons to add them in to your routine which are to build a specific muscle that is lagging behind in your compound exercises or to shape an already built muscle.
To target a lagging muscle, notice which one gives out first in a given compound exercise and work on that one.
Compound exercises target muscle groups.
They can be used to increase the intensity of your workout giving you the HIIT or High Intensity Interval Training effect.
This will stimulate the production of testosterone and growth hormones which are the keys to building huge muscles.
They also will force you into using all of your muscle's fibres triggering growth.
Squats and push-ups are a great example of this type of exercise.
To sum things up, use compound exercises to build more muscle and isolation to target ones that are lagging behind or even to fine tune a certain muscles' appearance.
Now think of real world applications in which you use your muscles.
Do you use only one muscle at a time? You most often use many at once.
Train accordingly and get the results you want.