Here in Canada, extreme couponing has never really taken off because stacking coupons was never allowed...almost every coupon I have ever seen since I was old enough to shop has always said limit one per customer or something along those lines. For us, couponing is really not practiced as most retailers will just discount items and put them in a flyer, or will have scannable coupons taped to the till so you don't even need to clip and bring.

Just FYI