Some assumptions are generally more important than others, and some may be of greater interest at different times, depending on the extent of their current and expected movements. For example, the oil price assumptions would be of greater interest at times when real oil price trends change direction, such as recently experienced.
The assumptions of the model can have a significant impact on the longer term forecast trajectory, as we have to take a view of the behaviour of these variables over a two to three year time horizon. Given the importance of the assumptions, a lot of time is spent deciding on them, and these discussions are an integral part of the MPC process.