Multi-Entry Business Visa : Maximum Duration of stay in a year

Hi, I have a multi-entry business M for China. Duration of each stay is 30 days. My question is can I go out of China every 30 days and come back again in a week's time, and continue this for the rest of the year until my visa is valid? Which means I will stay in China for almost 9 months a year on my multi-entry business M. Is it possible??
Is there a maximum duration of a stay in a given year for a multi-entry business M? Please help.