If you have the ability you can do as much as possible, but be careful not to spam the account. I do not encourage you to do much focus on FACEBOOK, you can do Twitter or signature. There are many ways to do this, wish you success.
I agree, for the Facebook campaign is not paid much. It is more profitable to signature campaign. Even Twitter campaigns are often paid more than facebook.
In general, everyone earns as much as he can. Although multi-accounts, even in several facebook campaigns involved ..