I gotta say we cruise Royal more than Carnival nowadays and we prefer the MEGA ships. Somehow they have mastered the pizza line even at the busiest times you're never waiting more than 5 minutes! We have also cruised MSC, same thing. Ready and Hot pizza no wait. When we were figuring our why this is it simply comes down to staffing. On Royal there is a minimum of 2 workers at all times and during peak hours 4-5! Same with MSC. Now that Carnival is going to be serving other nightly snacks at the pizza place I really hope they increase their staffing to cover both the pizza demands and other food options.
Also Royal and MSC did not have a pizza menu. Royal makes 4 types everyday all day and they kept the pizza "spots" filled. They were working to fill the holding area then pizzas are moved to serving position as soon as they were needed. Same system on MSC.