On the Menu: There's a reason for reservations

We always sat them -- we weren't going to call our customers liars -- but we also knew that, nine times out of 10, they had never intended to be parties of six.

It's easy to see why people would game the system and jump the line. After all, a party of five or six sits at the same size table, so why can't they make a reservation? These rules often seem arbitrary and frustrating to diners, who don't understand their purpose.

Every restaurant's guidelines are a little different, but they're all based on the same kind of logic: Keep your customers happy while also seating as many people as possible.

Restaurants like having reservations on the books, because it makes it a bit easier to order supplies and schedule the right number of staff. But reservation systems can be extraordinarily inefficient. Most diners want to sit down for lunch between noon and 1 p.m. and for dinner between 7 and 8 p.m. If all those spots fill up first, planning the rest of the seatings is a logistical nightmare, which becomes that much worse when some parties are late and a few don't show up at all.

Alternatively, first-come, first-serve seating can be great for some restaurants. They don't need to keep track of reservations, they can maximize efficiency and, if there's a bar, people will often spend more on drinks than they would have if they were seated immediately. That said, a fair number of diners simply won't go to a restaurant without a reservation, and if the number of diners is inconsistent, ordering and staffing can quickly become unmanageable.

Deb Mortillaro, a private chef and co-owner of Palate Partners in the Strip District, often avoids restaurants that don't take reservations.

"I can appreciate small restaurants who do not want to take reservations, because their seating capacity is so small," she acknowledged. But even then, she will typically call before she shows up. If she can't have a reservation, Ms. Mortillaro would like "an honest assessment from the [staff] about whether they can seat you or not."

And if a restaurant has an especially comfortable area to wait, they have a lot more flexibility. "If I'm at Cross Keys Inn [in Indiana Township] and I'm sitting in front of the fireplace drinking away, I probably could sit there for three hours," Ms. Mortillaro said.

So, should a restaurant offer reservations or not? That depends on a number of factors, including the restaurant's location, the available wait-space and proximity to other restaurants and bars. Legume Bistro in Regent Square and Avenue B in Shadyside both opened without accepting reservations, but quickly switched over once they realized that their clientele preferred to make plans in advance.

There are plenty of restaurants that thrive with walk-in only policies, such as Dinette and Abay in East Liberty, Yo Rita on the South Side, Il Pizzaiolo in Mt. Lebanon and Point Brugge in Point Breeze. Long waits are common at all of these restaurants, but that hasn't hampered their popularity.

At the new Salt of the Earth restaurant in Garfield, chef and owner Kevin Sousa, along with co-owners and architects Doug and Liza Cruze, devised a particularly creative solution. The downstairs dining room is filled with large communal tables with wooden, backless benches. It's casual and lively and takes walk-ins only. Reservations are required for the more traditional tables on the mezzanine.

"A lot of people just want to know that they have a seat," Mr. Sousa said.

A few tips:

Don't rely too much on the website OpenTable. While more and more Pittsburgh restaurants are using the site, even restaurants that participate often hold back some tables during prime times or don't put larger tables online. If you can't get the time or date you want, it always pays to call the restaurant directly and double-check.

While most restaurants give diners a 15- or 30-minute grace period to show up at the reserved time, it is polite to call if you're going to be more than five minutes late.

Diners should give restaurants a comparative grace period to have their tables ready. If the wait extends beyond that time, rather than comping drinks or dessert, restaurants might consider fast-tracking orders to ensure the affected tables quickly receive food and drink.