Circadian2 - 'Spanish' Lifestyle

Let's question how the 24-hour rhythm works.

Some would say it is important to eat, row and sleep following a regular pattern.  I do schedule morning rows when I am approaching an early morning race to get my body used to the timing of the race, but I do not necessarily row at the same time every day.  Some would say the continuous cycle of digestion works better if we eat and exercise and rest on schedule.  Does exercise-recovery work the same way? For many of us, making every day the same simply is not practical because of work or family demands and changes day to day.

And then there are the Spanish, working all week during the day but socializing much of the night on the weekends (or so I understand - plan to visit and see for myself next month). (Or compare the use of the siesta/resting afternoon and later nights with the US 40-hour week on a 9-5 schedule. And when the French went to the 35-hour work week, what was the effect?) Obviously, the body is able to work with such changes and/or on different schedules. But, just as we counsel against the weekend warrior syndrome (no exercise during the week, followed by intense/peak efforts on the weekend) as counterproductive, is there a downside to changes in the 24 hour schedule?

Is there an ideal schedule?