What you are suggesting is what already happens.
I am a teacher and work all through the holidays, except for a few weeks in the summer. I arrive at work at 7.45am and leave around 5pm. This leaving time is early at my school, with most teachers going home at 6pm. I also arrive later than most teachers at my school. I have half an hour lunch break and quite often less than that.
When I get home there is always things to do for the next day, week etc. This is not because of poor time management, it is because it is a huge job and there is not enough time to do everything within working hours at school. The work teachers take home is varied, it maybe; IEP's, marking, planning, assessments, planning for clubs I run at school, SEN work, co-ordinator [of subject or as in my case, subjectS] work, letters for parents and children, setting up displays, making power points, writing targets, researching an area I am going to teach, planning, filling out forms for adult students that maybe in your class, learning songs or music to teach, designing work sheets etc.
When my children go to bed I start working. This is for about one hour an evening, most evenings. When it comes to report writing I spend all half term writing reports and evenings leading up to the half term. At the end of each term, I spend a few hours every evening doing assessments and analysing tracking. There are also the hours you work late in the evenings for parents meetings on top of a full working day of course. If you are a school teacher governor you have to attend late evening meetings. You might help with the christmas or summer fair at the weekends. The list is endless.
There is no way you could plan a whole years work as every child is different and responds differently. It simply does not work like that. I can plan a whole weeks work for a class, but it will always need to be adapted or changed during the week if things don't go as planned or if a child isn't understanding something etc.
In summary, we already do have only about 5 weeks a year on holiday, if that when you take into account the hours we do during the normal working week! Teachers do work hard.
Hope that helps.