Some of you might alread know this
http://www.bodybuilding.com/fun/catwinstrol.htm
What I'm about to say goes for all compounds known to date : Steroids do not increase mass locally. The observance is noted because the injection breaks the fascia around the muscle, which possibly gives a muscle a little more room to grow. This is mostly temporary, and in the best cases very limited. Multiple injections would not increase the size in comparison. When the fascia heals, if it heals, it can lead to something called compartments syndrome, where a nerve is pinched between a muscle and its fascia. Leading to numbness quite often and in some cases to a paralysis of everything that nerve controls. This is not a frequent occurrence. This is rare, but my point was documenting that localized growth spurred by an injection is a myth.