See:
http://www.investopedia.com/terms/k/kited.asp
It's #2 I'm talking about, as you may be writing checks against funds you don't really have.
Also, the bank is going to be less than thrilled if/when it figures out you're doing this. They are giving you overdraft protection which is intended to cover slightly rubber checks (e. g. you have $200 in the account and write a check for $205), but it's not intended to be a long-term loan. When banks want to loan people money, they do research and have the person they are lending the $$ to go through a credit check. This is to be sure that you are a good risk for paying off the money. They will not loan money to you, or they will loan less money to you, if they think you are a less than optimal risk.