I have two girls, two and five years old. When they’re in our house all day, they start to go stir-crazy. Amazingly, if I take them out of the house and put them in a new environment, they calm down.
I don’t think adults are much different. Some are extroverts and are very comfortable talking to others for hours, some aren’t. Some people can go many hours without eating while others get “hangry” quickly.
When DJ’ing a wedding, love when cocktail hours are 1.5 hours or less, and they’re in a different room than the reception. This ensures people aren’t mentally exhausted from talking to others (even a chance to escape a conversation they’d like to get out of), they get extra stimulation by switching locations, and they don’t wait too long to eat.
Having your ceremony at 2pm, and dinner at 6pm is way too long in my opinion. Some Bride’s want to add so many safety-time-buffers to their timeline that they end up hampering the guest’s experience. Err or the side of going too quick vs. too long.