Four warning signs, in rough order of how often they catch people out.
The qualifying item list is narrow
A bundle that accepts only two-topping medium pizzas and plain breadsticks is a much smaller discount than one that accepts anything on the menu. Read the list before you read the headline number — the headline is chosen by a marketing team, the list is where the actual offer lives.
Specialty items carry a surcharge inside it
Common on family packs. Four pizzas with a dollar-fifty surcharge each is six dollars off the advertised saving, and it is disclosed in small type at the point where you are already choosing pizzas.
It is delivery-only and the fee is not included
A ten-dollar large pizza delivered is not a ten-dollar large pizza. Judge every offer on the checkout total rather than the tile price.
It requires a minimum you would not otherwise hit
Spending eight extra dollars to unlock a five-dollar discount is not a saving, however the interface presents it.
The one discount that stacks with everything
Almost nothing on this page combines. A percentage discount and a bundle price compete, and the site keeps whichever is cheaper. The single reliable exception is a loyalty redemption: because it comes off your account rather than out of your basket, it generally applies on top of a deal price. If you have a free-pizza redemption sitting unused, spending it inside a bundle order rather than on a full-price one is worth several dollars for no extra effort.
The habit that beats all of this
Build your basket, note the total, then rebuild the same food under a different offer structure and note that total too. It takes about ninety seconds and finds four or five dollars often enough to be worth doing every single time. Everything else on this page is detail — that habit is the actual advice.