When I spoke to the chap at EagleJet he seems to be conveying a similar message to the one illustrated earlier. Basically you buy the time and then depending on whether they like you, your ability and have a good attitude then they may keep you on. From what was mentioned this 'offer' occured around the 300hr mark with line training having obviously been completed by that time too.
Nevertheless I'm sure that each contracted carrier that EagleJet do business with has their own take on the situation and will act differently.
Hope that helps.....