Annual progression should be taken seriously, as this is considered confirmation that the student is on track. If work is not satisfactory, remediation plans must be communicated as a condition of progression. Other options include continued enrolment for the MPhil only, or withdrawal from the programme. Authorising progression into the fourth year (seventh year part-time) also means that the supervisory team are confirming that the student can be allowed to submit their thesis without permission from the department.
Taking these milestones seriously and addressing any challenges arising early is key to the overall success of most PhD projects; in more complex cases, documenting concerns with the project and/or contextually for the student through the PhD Journal/Log, and as part of the progress review and upgrade processes, even if they cannot be immediately or easily addressed, is also important. This creates a paper-trail of accountability and clarity for all sides, and might help if extensions, interruptions, or special exemptions from regulations become necessary later on.