How we save on eating out

First time posting so I hope this fits the frugal criteria.

Costco has many gift cards for dining and entertainment. Often they have $100 in gift cards on sale for $50 for one of our favorite local (small business) restaurant. We load up on them as a way to eat out once or twice a month and also when we want to take friends/family visiting out for a nice dinner.

The second part to this is the restaurant has more money saving options once you arrive

a) half off appetizers at happy hour Mondays b) Buy one get one entree half off at next visit when you save the receipt from current visit

We just save the receipts or go on Mondays. I'm terrible at math, but after paying $50 for $100 in gift cards, then those discounts in restaurant just make it even less to eat out.