This is how I try to explain “the zone” sometimes:
– Suppose that a task takes 60 minutes to complete. Can you break it to six ten-minute intervals and complete it in six days?
60-minute tasks that require you to be “in the zone” cannot complete in six or seven ten-minute intervals.
Managing organized complexity 
/nerd mode on
Correct, your TLB is invalidated on each ten-minute interval :) Someone must optimize human brain context-switching.