Depends on the teacher.
Personally I would do between three and four hours after hours every day, another 5 - 6 hours at the weekends and an average the 3 hours a day during the holidays - every day but ... I teach history and like to keep up to date with newest works while a teacher in another subject mightn't have the research to do that I believe is necessary for the histories.
Having also taught primary school in my first 10 years I do less now as a high school teacher than I did now and from talking to primary colleagues believe most of them are also doing similar hours during the term time but more during the holidays e.g. all the primary teachers at my school (K - 12) were in their rooms on a number of days during the holidays to make them ready for the arrival of the students just doing things like covering the books, putting up posters, arranging the furniture, reading up on the past records of the students to prepare lessons for the full range of students.
That being said there are also teachers who turn up in time for first period and leave as soon as the day ends (which to some people it may appear that I do but that is because I do a lot of work at home as I find I work better in my study there) and then do nothing else.
So - teachers put in as much work as they need to do, want to do and it does depend on whether it is seen as a 'job' or a 'vocation'.
