problem is Swept even when you have the whole group of the training team wanting a certain thing the accountants will always go for the cheapest option.
The low hours cadetships have significant tax advantages for the company. They basically get a free pilot for two years.
And I doubt very much if anyone has analysed it. Airlines are lucky to know what's happening in 3 months time never mind years in advance. Until the supply dry's up they won't do anything about it. FR and EZY are pumping through enough 737 and A320 pilots to supply the market for years. The can afford to over crew significantly because if the crew don't fly they don't get paid. I don't think the supply will ever run out on those types.
There is no problem with FO's there are thousands of them, the thing that company's are struggling to get is high experienced Captains with training experience.