How does NEC4 clause 64 work?

Clause 64 lets the Project Manager take the assessment out of the Contractor's hands, but only on stated grounds and only to a timetable. Under clause 64.1 the Project Manager assesses a compensation event if the Contractor has not submitted the quotation and details within the time allowed, if the Project Manager decides the Contractor has not assessed the event correctly and does not instruct a revised quotation, if the Contractor has not submitted a programme or alterations to a programme which the contract requires, or if the Project Manager has not accepted the Contractor's latest programme for one of the reasons the contract states. The assessment uses the same rules as any quotation, so it is Defined Cost plus Fee under clause 63 with the actual and forecast split at the dividing date, and where there is no accepted programme to work from the Project Manager uses its own assessment of the programme. Under clause 64.3 the Project Manager notifies the Contractor of the assessment and gives details of it within the period the Contractor had for submitting its quotation, counted from when the need for the assessment became apparent. Clause 64.4 is the sanction: if the Project Manager does not assess within that period and the Contractor notifies the failure, and a further two weeks pass without an assessment, the Contractor's quotation is treated as accepted. Once notified, the assessment is implemented under clause 66 and the route to change it is dispute resolution, not a revised quotation. Three things go wrong. Project Managers use their own assessment as a negotiating position, notifying a bare figure with no details. Contractors treat it as an opening offer and keep resubmitting quotations that no longer have any status. And where the ground was that no quotation was submitted, there is nothing for clause 64.4 to deem accepted, so the Contractor's only protection is to have quoted in time.