@RFZ, you can extend it for any number of times, thats not a problem, Before i had single entry VISA with 30 days validity, but i extended it for 6 times before i got my work VISA. so no issues, just can extend as many times you can.
NOTE:- Before someone informed me that we can extend it 11 times, but hence i have seen people extending it more than 11 times. So guess everything is possible.