I was dx'd with CC in Dec., 05, 4 polyps, 2 of which were cancerous. Had a bowel resection in Jan., 06 with temporary ileostomy. Ostomy was reversed in May, 06. My CC turned out to be stage I, though they were not certain until after the resection was completed and the biopsies came back. I had my first follow-up colonoscopy on Jan 12, 07, and it came out completely clean (well, one small tab at the area where my colon was put back together. The doctor determined it was NOT a polyp, only a small mistake in the surgeon's sewing skills
) The doctor performing the follow-up colonoscopy said I was good for three years before my next scope should be done.
BUT - every case is unique. Follow your own doctor's advice. (And every three months does sound excessive to me, too!)