CO could get much better use out of their equipment if they went double daily and instead of having the aircraft on the ground at EZE from 0920 till 2150, they returned it straight away to IAH.

For this to work they would have to adjust the times of flights and look elsewhere in their system for spare capacity. Kinda tough.

The flight time of 10 hours 30 mins it would be tight to use that aircraft for the next return flight every day.

However this could be a possibility.

FLIGHT 1
IAH 1900
EZE 0720 next day
EZE 0900
IAH 1730

FLIGHT 2
IAH 0900
EZE 2120
EZE 2300
IAH 0730 next day

This would meet the needs of night and day flights and achieve better aircraft use. However it would take just one major delay to screw it up.