It's not common courtesy to do things in an efficient fashion. I have a little nuclear family of 4. I do the ordering while my wife finds a table and texts me the location. I order quickly, no dilly dallying, no taking up extra space in the queue. By the time I pick up the food, then drop it at the table, then head back to the condiments/napkins/forks set up, my wife has the kids sat, clean and ready to go. THAT is the best, quickest, smartest way to operate. It reduces the overall amount of time we are in the restaurant, while ensuring that we turn the table over quickly.
Let me tell you what isn't efficient. 4 people in line, 2 of them under 5 years old. Waiting to order food as a group. Staring at the menu, deciding, changing minds, etc...taking up space. Then we all order, then we all wait for the food, then we all stand around in a big group, holding food, trying to find an empty table. Then we finally find a table. Sit down, get back up to go to condiment bar. Then get back, then clean up the kids, then start eating. This way takes much longer and ensures we are both occupying space in the restaurant for a longer amount of time, and at absolute BEST, holding the table for the exact same amount of time.