I'm a former waitress with over 12 years of experience.
Where I worked they did not automatically add on the gratuity for larger groups. Sometimes that worked to our advantage and the customers left more (once I received a tip of $63 from a group of 12 people, and this was in a diner so the meals were not that expensive) and sometimes it was a disadvantage when customers left very little. It was the luck of the draw.
Now, as a customer, I am MUCH more lenient with servers when the restaurant is extremely busy. I know that I am not their only customer. I've been there myself. I used to work one night a week by myself. I could be waiting on 50-60 people, all at various stages of their dinner. Plus I had to answer the phone and take to-go orders, run the cash register, and clear tables by myself. Some nights it was terrible. I was running around like a chicken with my head cut off, trying to meet everyone's needs. Most customers were extremely understanding, and even if I only made it back to their table once to check on them they still left great tips. Occasionally there were the ones who were oblivious to what was going on around them and would complain about the poor service. Well, I'm sorry, but I only have two hands and can only do so much.
Where I worked servers started out receiving $2/hour as their wage. Then it went up from there. I got up to a whopping $3.25/hour. Most people know that we don't make minimum wage, but some do not.
Also, we are taxed on 8% of the the sales for the hours of our shift. If someone stiffs us, for whatever reason, then we are actually paying out of our pocket for the privilege of waiting on them. Yes, I understand not tipping or leaving a very small tip for poor service, but it really should depend on why. But it was the non-tippers that came back time after time after time that really bothered me. Giving good service and then being stiffed just because they don't believe in the tipping process? Then eat at home and cook your own food.
I understand the frustration of food taking too long, and I did try to keep track of that and would often go to the customer and explain what was taking so long. Maybe the cook had the food almost ready, and then dropped a burger patty on the floor so had to cook a new one. Or maybe the cook was working on a rather large to-go order. I found that if I explained what I knew, they were less apt to be upset about it taking too long. And I always left a pitcher of water on tables for larger groups, many times I would leave a pot of coffee as well, or even a pitcher of Coke if that's what most were drinking.
I tried to anticipate their needs before I was asked, and I do understand not wanting to wait for silverware after your meal has arrived. It's the server's responsibility to make sure the customers have everything they might need (silverware, ketchup, napkins) before their food comes.
I kind of understand why some restaurants automatically add a gratuity for larger tables, because a larger table does take more of the server's time. If I have a 4-top and a 12-top, the 12-top is going to take longer for ordering, bringing their food out, refilling their drinks, etc. But I also understand the customer not wanting to adhere to the auto-grat of 18% when the service was lacking. It's kind of a fine line, really.
Like I said, I am very patient with servers, and if I can see they are really trying to keep everyone happy, and they are apologetic if the food takes awhile, or they haven't been back to give me a refill, I still tip well. But if the server is chatting it up with other tables, and not paying attention to her other customers, or if she is behind the counter chatting with other servers, then the tip gets lowered.
I will say, I'm very glad to be "out of the business" though. It's a hard job, and until a person has worked as a server they really have no idea how difficult it is at times.
