Based on what I've read it is more or less the same model we have in my country. Employment contracts are either fixed or indefinite term contracts, you can't renew fixed term contracts indefinitely and they are used in specific situations, one of them being to assess or test someone's abilities before offering an indefinite term contract, so 3 months is a short term but not really in the sense that your new employee doesn't necessarily needs to master the job in 3 months, you just need believe or see that they are learning and being as good as other hires in that amount of time.