If the first plane needs 3 hours to return to service, you delay the first group of passengers by 2 hours and the second group by one hour. There's no need to delay the rest of the day's flights when the plane is fixed.
The person hours of delay is still 2x200 + 1x200 = 600.
Imagine a route with 6 planes a day, 2 hours apart. The first flight of the day develops a problem that'll take 3 hours to repair.
Is it better to delay one plane by 3 hours; pay 200 passengers compensation; and waste 3x200=600 person-hours?
Or to delay six planes by 2 hours; pay no compensation as only 3+ hour delays get compensation; and waste 6x2x200=2400 person-hours?