Well Dave, I have never known NCL to be stingy with food and if we wanted more of anything, it was provided. In Cagney's they have menu items that are available for the $25 surcharge and other items that carry an additional charge. You can look at any of the menus at the reservation desk prior to booking a reservation.
If you don't wish to pay an additional charge you can always eat in the main dining room, buffet or Blue Lagoon. I must admit, half the fun is the variety of eating venues NCL has to offer, I always know if I am on NCL I should budget extra $$ so I can try all of it, and for us it has been worth the extra charge.