The most contractions I've managed to endure was 30, and that was VERY rough. Actually, that was during an apnea walk. When I'm very, VERY relaxed, my contractions will usually start at the 2 min mark, like clockwork. I was REALLY surprised during Martin's course in June, when, while doing static apnea in the pool, on my last one my first contraction didn't hit until 2:30!
Todd