In addition to what Terri Lynn said, restaurants are more likely than they are in the US to have only one seating. In other words, if someone was at a table from noon to 1:30, they are not necessarily going to seat you at that table if you come in at 1:35 (even if the sign out front says they're open until 2:30 or 3).
However, there are plenty of places to get food between 2 PM (the "end" of lunch) and 7 PM (the "start" of dinner). If you want a formal, sit down restaurant, that works better if you plan to eat at standard times (12-2 and 7-10). Many people don't start their dinner until 8. If you want crepes, or Chinese, or sandwiches, or souvlaki, or pizza, you can eat at any time.