Are parent/teacher conferences not built into the schedule as working hours? If I recall correctly from my mother, who was a school teacher, they did these twice a year and those eight hours were counted as one of the days that they worked in their contract. Maybe that is not universally negotiated.

As she was a special ed teacher, she also had a whole slate of other meetings with parents to go over IEPs and testing, and if those were before 8 am or after 3 pm, she was paid an hourly rate for those meetings.