A: Oh, how I share your feelings about meetings. No, there are no such guidelines, although this issue should be considered as part of the agenda for remodelling the workforce, which emphasises the need for teachers to have a good work-life balance. Speak to other staff and air your feelings.
Sometimes a newly qualified teacher is like the little boy commenting on the emperor's new clothes - you state the obvious that others who are used to the status quo accept without question. Every meeting should have a strict start and end time as well as an agenda that should make it clear whether you need to attend.