The test comprises 5 sections according to the Regulation however the CAA test profile still comprises 7 sections as it was never aligned with EASA.
In order to take the Assessment of Competence you need a sign off from the CFI, you will not get that if you are not ready.
AMC1 FCL935 states:
All relevant exercises should be completed within a period of 6 months. However, all exercises should, where possible, be completed on the same day. In principle, failure in any exercise requires a retest covering all exercises, with the exception of those that may be retaken separately. The examiner may terminate the assessment at any stage if they consider that a retest is required.
A partial pass wiil be awarded at the discretion of the Examiner relating to one item that was unsatisfactory. A failure of the theoretical knowledge, or multiple items would constitute a full failure.
A test might also be incomplete and the 6 month window allows sufficient time to complete it.