Beginning bodybuilders often train in a haphazard fashion in the gym.  They walk into the gym, hop on the nearest free machine or bench, and then bounce around the gym, hitting random body parts on random machines, with no rhyme or reason.

Intermediate bodybuilders are a bit wiser.  They find a routine and stick with it.  They know to start with the same two or three essential compound movements each time, then to move on to isolation movements.  They know what exercises they will do, but they do vary the rep/set scheme to ensure some variety.

Once you’ve been training for 3-4 years, you begin to get a feel for what works and what doesn’t.  More advanced bodybuilders often utilize a technique known as ‘instinctive training’.  They enter the gym knowing what body part they will be training.  They start on the treadmill for a few minutes of warm up.  If they’re feeling strong, they might select a heavy compound movement for low reps, heavy weight.  If the mind-muscle connection isn’t quite there yet, they may start with some isolation movements to get the blood pumping into the area, and make it a medium-weight, higher-rep range day.

Advanced bodybuilders know their bodies.  They are able to determine the limits their body can handle.  They know when they’re ready to give 100%, and they know when it’s safer and wiser to only give 85% and train a bit longer.  They understand their capabilities and limitations thanks to years of training, and they are able to more effectively grow as a result.  They waste less time, and they face fewer injuries, because they are able to adjust training protocol to match the demands of the gym and the available resources of their bodies.