I'm not entirely sure, for me a applied for a MDD role at Northern just over 3 years ago and was invited to the assessments which I passed (the position had already be filled but they wanted me to do the assessments anyway incase any more roles came up in 2017). I have applied for the same position with Northern the other week, this is the first time in 3 years this job has been advertised and I'm hoping that having already passed the assessment through them it may help me somewhat.