Most of the time there difference of price exists so do you withdraw bitcoins from one exchange and sell at higher rate exchange?
I don't, I only use one exchanger to easy to control my balance, one exchanger is enough for me because I have trading skills, I can easily earn profits with my skills.
it is good that if you are focused in one exchange and make things work,i do personally use multiple exchanges and use arbitrary trading when ever i find an opportunity to make some extra dough ,so i do use multiple exchanges all the time and being an alt coin trader i have to use all the exchanges.