Actually it's not true, it can harm you though. You can work out an area of muscles by lifting weight and try to increase the wieght by 10-20% on each of your next reps. After that, let that area of muscles rest for at least 24-48 hrs before start training again. Within that time, you can start to train on other area.

for example:

Monday: Upper muscles: shoulder, biceps, triceps, chest, and forearm
Tues: Mid section: Abs, hips, back
Wed: Lower: Leg muscles

Take good supplements when you're working out, preferably proteins.

Taking 24-48 hrs break will allow your muscle to rest and absorb those nutrients that you took and develop better.