Most fast casual restaurants, like PF Chang’s and The Cheesecake Factory, do not take reservations. Those types of restaurants are high volume joints that can easily seat over 300 people. Their kitchens are designed and staffed to produce food at a lighting fast rate, and when everything is in harmony, they can make really good food.
The key to success in one of these restaurants is to get the dining room full and keep it full throughout service. Ideally, you are seating a new table every two to three minutes, which keeps the kitchen cranking at a steady pace. They accomplish this task by “going on a wait” and handing pagers out to their guests. Each guest comes in, is quoted a length of time, a name is taken and a pager is given. Then you wait until they buzz you and you are seated. They operate this way because they already know that a whole bunch of people are going to show up and they can accommodate all of them, at a faster pace, it they make everyone wait for a table, rather than reserving one. It also helps to keep things sane in the kitchen. The pay off is big sales on not so high check averages.
Fine dining restaurants and smaller establishments take reservations. Taking reservations helps them to control the flow of tickets into the kitchen, they might only have two or three cooks, and allow them time to make quality food in a reasonable amount of time.
Reservations also help them control costs. If they are booked full for Saturday night, it is easier for the chef to judge the amount of food he will need to order as well as the amount of labor he schedules. Most mom and pop places make their bread on the weekends. Wasting food and exceeding the labor budget can tank your week’s profitability in one night.
A reservations only restaurant has an air of exclusivity as well. Take a place like Rao’s in NYC. Their tables are booked for all time by regulars who hand the reservations down from generation to generation. It is possible to get a table, but you have to know someone who “has a table” there and dine in their place. I’ve never had the pleasure of dining at Roa’s, but I would jump at the chance.