How often you train, how long you train, how you cycle your training and the exercises you perform while training are all indications of how good your muscle building program is.

How Often Should You Train?
Some muscle building programs advocate that you train each body part only one or two times a week.  If you are building massive muscles and your workouts are so intense your muscles require more than 24 hours to recover, then training twice a week is fine.  But, if you want big muscles like an olympic swimmer or a male gymnast you ought to work like a swimmer or gymnast - several workouts, more than once or twice a week.  The right exercises done at the right intensity three to four times a week will give your muscles time to recover and get bigger.

How Long Should You Train?
Also, a workout should be less than an hour.  Testosterone levels are at their highest about 27 minutes into your workout, and by 45 minutes into your workout cortisone - the stress hormone that promotes body fat storage - levels increase significantly.  So 40 - 45 minutes should be the most time you spend in the gym.

Cycling Your Training
Your workout has to be productive if it is going to be short.  You should cycle your routine so you are always challenging the muscle - working it in different ways.    Muscles will become accustomed to any one routine after a while, so you should  alter your workout before the muscles adapt and stop growing.  Don't switch before you see major progress, though.  Most good programs will have you switch your routine monthly.  This will also keep your workouts from getting boring.

Cycling the Intensity
You should not only cycle your exercises, but your intensity, too.  Push yourself almost to the edge of overtraining, then back off for a little while, then push yourself to the edge again.  This will engage all the fibers in your muscles and keep your muscles working through the entire workout.  An explanation about why interval training works to build muscle faster can be found in this article.

Another way to make your workout more productive is to use bodyweight exercises.  Because you tax several body parts at a time with bodyweight exercises, they are more efficient.  Bodyweight exercises do not isolate one muscle group - it is a more natural motion.  You can use push ups, chin-ups, lunges, squats or dips and all the variations of these exercises or any other bodyweight exercise as part of your routine.  Changing the motion or adding weights to the bodyweight exercises will vary the intensity of the workout.  Weights added at the belly will make a dip or a chin-up more difficult, the intensity of a push up is increased when it is done on a decline instead of level.

So, vary the intensity and exercises performed using bodyweight exercises, work out 30 - 45 minutes only, stop spending hours in the gym. Soon you will see considerable progress in your muscle shape and size.