As someone with rural/countryside roots, I recall similar advice on physical labor: it is best to work at a steady, consistent pace all day long
without getting sweaty or breathless. You'll avoid (or postpone) dehydration, remain more alert and calm, and thus it is much easier to switch tasks immediately.
As a tree planter of several seasons, I've realized that this advice works remarkably well. Pushing yourself, sweating, drinking stimulating beverages instead of plain water etc seems to give you an edge while planting, but it's kind of deceptive in the long run IMO. Steady, moderately paced, but consistent, non-stop work is more effective in the grand total.
Then again, all this might come down to whether one is a "long distance runner" or a "sprinter" by personality and bodily characteristics. I guess I'm somewhere in between, but, approaching 40, these "100 meters in 9.2 seconds" daily life dashes are somehow starting to lose their appeal. Howdy, middle age!