I am just speaking from experience. If we go to a popular CS, such as Pinocchio's or Cosmic Rays, at a busy time, I wait in line for at least 20 minutes to order food, and then carry the food to the table we usually have to wait for (5-10 minutes). Then, I have to go back to another station and order the kids other food, since each area you only order certain foods (ie one station is burgers, one is salads and sandwiches, and one is chicken) and not everyone wants the same thing or same type of food. Add another 20 minutes. Walk back to the table with the newest food. Then we have to go to the condiment bar (add 10-15 minutes because everyone else has to go to the condiment bar). By the time we are all ready to eat our food together, it has been an hour (literally, an hour has passed, and we have our CS food, sit down to eat it, and it tastes good because we are so hungry and have waited an hour) then we have to take our restroom break after sitting and eating our meal for 20-30 minutes. Add 15 minutes for restroom break (yes, the restroom break counts as time in CS meal, we have 3 little girls - ages 8, 7 and 4 - part of the whole mealtime experience. CS meal has taken up 1 hour and 45 minutes.
Contrast all this to TS meal where even waiting 1 hour for seating we go into nice air conditioned restaurant, order our food, (mom is not wore out by standing in line and then carrying food to the table, then going to condiment bar, etc, etc) and we can sip out drinks and nibble on appys while waiting for our entrees. We can take restroom breaks (kids 8 &7 yr old can go by themselves in TS places). A very leisurely meal and it has taken 1 hour and 45 minutes and we are not all stressed out!!
Yes, CS can take shorter times but that is at less busy times, and less busy places in general. Food courts at hotels (POR for example) have the same issues as theme park cs placs. Just our experience, and we prefer the less stressful TS over CS.