No, you need to demonstrate that you are aware of a prescribing issue and address it.
For example, if a new guideline is issued suggesting that the management of condition X should change, there is little point analysing past prescribing to demonstrate that you did not comply with the new guidance. You do need to demonstrate that you have considered how the new guidance should be implemented, and plan to do so.
However, if you look at a prescribing error, it might be worth assessing the current practice to determine how significant a problem you have uncovered. This could help you to plan change.
No, provided it gives you an indication that you need to consider prescribing in this area. A regional or even national audit may do this; alternatively an audit by a member of your team could be the stimulus. You need to be clear what current practice is, and consider the need for change.