I only have experience with booking 2 rooms under my name (not 3). In all instances, breakfast coupons were automatically provided in the key folders for both rooms. I've never had to ask for them. I suppose if a hotel was being stingy and insisted on coupons for only 1 room, you could just stop by the front desk in the morning and say "I never received my breakfast coupons. May I please have 2?" and I doubt they'd blink an eye.