Traditionally energy availability is one of the biggest factors in what we eat, what we store, how we prepare it, and how and when we cook it
Energy for light, cooking, and food preservation used to be very expensive in time and money until the last century or so. It still is for around half the world’s population
When your only clock is the rising and sinking of the sun, routine becomes more prevalent and necessary
Your modern western stereotypical breakfast/lunch/dinner is now more a factor of the working week and the clocking on the "job" requirements, than energy and time availability. Check out some independant self-employed people, and see what strange food clocks they develop :-/
For example: The switch from the main meal being in the evening instead of midday only happened in the west in the last 100 years or less. Post WWII in many cases. Some western cultures still have their main meal at midday though
Also post WWII, post "Ford" era, the midday main meal was enjoyed at home. Farmers went to their house, workers walked home as you could only work where you could walk too due to lack of energy resource (time and money again). Many more people where self-employed and worked from home too. So going home for a big midday meal was not an issue, and having a long midday break was reasonable
Cultures have changed fast in the last century, what will happen next? I am going for 3D printed food machines in your pocket, though hopefully not an iChef as that would only use a limited ingredient menu :-)