It doesn't have to be curtains when demand is high, let alone that you can't run an airline on cadets alone. There have to be experienced FOs. Quite a few have to make it until command, especially given that internal promotion is the preferred method of filling CPT vacancies (again, due to the training philosophy and the unwillingness to water it down with externally trained candidates). But, nonetheless, it's a zero-hour contract - and people need to keep this in mind at all times. They might use any given pilot up to the legal limits when there's a lot of flying (not anytime soon). They might not use them at all when there's no flying. Or they might use the cheaper pilot of the two when there's a choice.