I do think it varies hugely between schools, phases and subjects.
A school fighting to get out of / not drop into Special Measures / RI is likely to involve some very exciting hours.
Any school going through a period of change will involve longer working hours - the new National Curriculum will involve completely re-writing many schemes of work in many schools, which puts a burden on subject leaders. In small primarties a teacher may head up 3 or 4 subject areas. Equally a new head or a push towards an upcoming Ofsted will increase hours.
School culture also varies. In some schools, it is expected that schemes of work and resources will be re-used from year to year with little modification. In others, either due to variable cohorts, mixed age classes or simply 'this isn't the way we do things here', such recycling is seen as less acceptable.
From observation, the daily grind of primary is somewhat higher than the daily grind of secondary in many subjects - for one thing, a typical day in a 30 pupils primary school class may produce 90 - 120 pieces of work to mark - BUT secondary has more dramatic peaks and troughs in marking load.
Wihin secondary, workload will vary greatly between subjects.