What is the best rep range to get a chiseled physic and what to gain mass? PDF Print E-mail
 
The idea that low reps programs will give you muscle mass while high reps programs will get you ragged is oversimplified to say the least.
If you focus on heavy loads (above 85% of your 1MR) but you do not lift for many sets to create sufficient volume of training, you will get stronger but you will not necessarily stimulate muscle growth.
Nutrition and sleep plays a huge role too. Even if you lift heavy and create a big volume of training if you don't eat sufficient amounts of food and you don't sleep enough time, you will not give your body the necessary building blocks and time to use them and you eventually burn out instead of gaining mass.
Getting ragged on the hand is a matter of fat level percentage. If you fat level is really low (below 10%) you will look ragged. So you have to focus on programs that burn fat and elevate your metabolism and adjust your nutrition for this purpose.
Regarding reps and sets. It is not so much how many reps or how many sets you will do in your program, it is how much total effort you produced during your session.
There are many ways to produce the same workload. For example if you lift 50 kg for 3 sets of 20 reps that's 3000 kg of work. If you lift the same weight for 6 sets of 10 then you also produced 3000 kg of work. So there are many ways to skin the cat and no rep, set method should be carved in stone.
To educate yourself about the above concepts you may also read the following article:
“Liberate yourself from Classical weight training” from Charles Staley.

You have to know though that your body has the ability to adapt to the reps before adapting to the exercises. This means that after a certain period that you use the same reps your program starts to loose it's effectiveness because your body is adapting to the specific rep range.
It is a mistake to keep doing the same program for long time. You should have a plan and change your reps and exercises to shock your body. Changes should not be made too early though.
A good rule of thumb that you can use is to change your program every 4 to 6 weeks.
Change the rep range first and about half of the exercises (or you may use different variations of the same exercises). This way you give your self, sufficient time to make progress and you change the parameters just as your body starts to adapt.
Check the articles on the fat loss and Muscle building sections for more information.