There is no requirement for an annual assessment on your bank, but realisticly, if you don't do it, how do you know where you sit come exam time?
I do quarterly cumulative (cumulative through the exam period) reports which are shared with the Board of Directors (we take CRA seriously here)

as well as a full Preformance Examination (yup just like the examiners do) on an annual basis.
When you have your eventual exam they do ask for your board reports or self assessments. Having nothing isn't going to penalize you, but if you put yourself in your examiners shoes, how would it look to you? If the bank isn't paying any attention to CRA during the period of the exam, how can they possibly put together a performance context of any value?
Another hint...I've seen MANY of my internal PE results repeated word for word in my actual PE from the examiner. When you provide them with a factual assessment, as well as the performance context in a document structured exactly the same as theirs, it's only human to cut and paste the stuff that makes sense into the final exam
Second hint, don't overrate yourself in your internal PE. Don't beat yourself up if you don't need it, but try to be objective. I've seen folks rate themselfs outstanding, outstanding, outstanding...when they actually should have been outstanding, low satisfactory, satisfactory. This type of internal exam is going to end up in the round file and won't establish any credibility with your examiner when the real exam comes around.