At the time it felt a slightly patronising waste of time but at a parents eve in Feb the head teacher ran a session for parents and students to do together, there was a talk to start with explaining when the school expected as a minimum from the students and a bit of research summary about (variously) sleep, electronic devices, distractions and study/revision methods.
Then there was a worksheet to go through, parents with the student about the ways a parent can help the student study and what kind of help the student wanted from their parent.
The student set their own targets for the timing and type of activities they would do then had to say how they wanted supporting in doing those things (eg snacks, quiet space, any materials they needed) and what they wanted their parent to do if the parent noticed they were not doing what they planned (answers were open ended but different students said 'nagging', 'take away my xbox', 'sit with me and help', 'just remind me then leave me alone'). It made a kind of contract.
In retrospect I think it was quite a useful activity as I know what ds is aiming to do and what he wants from me and I know I have the school's backing to limit what I can do to the things discussed then. The head is a very knowledgeable one with a research background who said that by this age any extra parental pressure will not help so we should save our energy.