Can a person stay in China as long as the work visa is valid i.e., 90 days?

I was issued an employment visa in India by the China Embassy new delhi on the 30th March which was valid upto 30th June. And the duration of stay was 000. The officer at the PSb in China said that I could stay in china for 30 days only and had to go out of China and return after 30 days with a new visa. Is it the case. I had applied for residence permit within 30 days. I have a doubt in the duration of stay in the employment visa. Can a person stay in China as long as the visa is valid i.e., 90 days. Please clarify. Thanks