poll of nearly 200 heads and deputies has found that 63 per cent thought the agreement had actually increased their workload, and more than 24 per cent said it had made no difference.
Some respondents summed up the mood, complaining that the increased organisation had created more work. Tasks previously done by teachers were now falling to heads, as the latter desperately try to stick to the terms of the agreement for their staff.
"Headteachers and their senior teams have not been treated well by it," said John Johnson, head of the Campion School in Hornchurch, Essex.
Another secondary head said: "On a bad day, there is resentment that it did nothing for heads."
The workload deal for classroom teachers has remained firmly in the spotlight since its introduction.
This summer, the NASUWT launched a campaign to call on teachers to report their schools if they were failing to implement the agreement properly.
Unions have come down hard on schools accused of cutting short classroom teachers' planning, preparation and assessment (PPA) time, or of failing to provide support staff for clerical tasks, for example.
But what of the heads themselves, and their deputies and assistants, who have worked so hard to put the changes in place?
Recent figures from the School Teachers' Review Body paint a somewhat bleak picture. Its survey showed that secondary heads worked an average of 59.5 hours a week in 20078, up from a 14-year low of 57.6 hours last year.
In primary schools, heads worked an average 55.2 hours a week in 2008 - about the same as they did in 1994, and up from a low of 52.9 hours in 2005.
Under the agreement, headteachers not only have a right to perform the day-to-day management of the school, but should also be "freed up to think, analyse, plan or carry out any of the associated activities so their school has a direction".
The governing body and headteacher must decide between them how much time is given, depending on the particular circumstances of the school. Anyone in a leadership post is entitled to leadership and management time in proportion to their role.
School leaders also have the right to planning, preparation and assessment time on any teaching timetables and, in the same way as teachers, should not be required to carry out routine administrative and clerical tasks.
The governing body also has the legal responsibility to ensure a "reasonable work-life balance". The definition of "reasonable" is, of course, left open to interpretation.
The Association of School and College Leaders, which represents secondary heads, blames the ever-increasing pressure of government initiatives for this lack of progress in workload reduction for headteachers.
Recent research suggests that leaders of primary schools are not getting their dues under the agreement either, because they are much more likely to have a teaching timetable and have fewer staff to whom they can delegate.
A survey of mostly primary school leaders conducted by Keele University earlier this year found that two-fifths were still working more than 60 hours a week. Almost half were working between 49 and 59 hours, in excess of the working time regulations.
The study also found that more than 80 per cent of school leaders carried out administrative and clerical tasks that did not require the professional judgment of a teacher, such as school meals supervision, collecting money or conducting risk assessments.
Dr Steve French, from the Centre for Industrial Relations at Keele University and the report's co-author, concluded that there was a "persistent culture of excessive hours and expanding workloads, which are clearly not effectively regulated by working time legislation or by the arrangements arising from the national workload agreement".
The report also found that almost half of heads received no dedicated headship time, a fact that the Training and Development Agency for Schools has conceded is a problem.
Howard Stevenson, deputy director of the Centre for Educational Research and Development at Lincoln University, said the reason heads were still working just as hard in both sectors was because of the "raising standards" aspect of the agreement.
"Raising standards trumps workload every time," he said, "You may not be putting up displays or doing clerical work, but you are now working damn hard to raise standards.
"New Labour said people wouldn't get something for nothing, and that is the pay-off.
"Also, you can tell a headteacher to employ a parent liaison officer to meet parents to reduce their own workload, but some heads enjoy that aspect of the job. You start to narrow the job down to something many heads don't like, and they are then whipped even harder to get results."
Mr Stevenson said that further aspects of the remodelling agenda, including the introduction of performance management and teaching and learning responsibility (TLR) points, had added extra pressures. "Introducing TLRs created a massive job and was a torturous process," he said.
The national workforce agreement highlights the responsibility of governors and local authorities to ensure a reasonable work-life balance for headteachers.
The National Governors' Association had worked hard to make its members aware of the agreement. Phil Revell, its chief executive, said part of the problem was cultural.
"Some deny it, but the reality for the vast majority of schools is that they have a `hero head', leading from the front," he said.
"Those who come to national prominence are like this, and heads are encouraged to embrace all this workload and responsibility."
Mr Revell said it was the job of governors to persuade heads to take on extra staff to whom they could delegate, and thus create a more manageable job.
"Governors, if they are doing their job, should be monitoring the head's workload," he said. "If a head is under pressure, the governors have a duty to act."
He added: "Saying `you aren't coping' isn't easy, but if they leave because of stress, the fallout will affect everyone, and finding a new head could be the least of the problems."
How heads benefit, pages 30-31
What the agreement means for heads
Under the workforce agreement, heads should not have to do admin and clerical tasks. The school governors are responsible for making sure heads are relieved of these tasks.
Overall hours should be "reasonable", and the governors must "have regard to" the work-life balance of the head.
Heads and those with leadership responsibilities are legally entitled to "a reasonable allocation of leadership and management time".
Heads are also entitled to "dedicated headship time", specifically for the strategic leadership of their schools. There are no specific rules or guidance about what constitutes an appropriate amount of headship time, and that should be decided between the head and governors.
Heads with any teaching timetable are entitled to 10 per cent planning, preparation and assessment (PPA) time on top of their other allowances during the timetabled teaching day.
Where three into one leaves time left over
Carolyn Howard is head of three small rural primaries near Wisbech in Norfolk, including Tilney St Lawrence, Walpole Highway and Terrington St John.
She started as head of the 95-pupil Tilney St Lawrence in 1999, but found it difficult to fit leadership and management alongside a teaching load that filled half her timetabled hours.
Nine years on, she is head of all three schools, has no teaching timetable, and has developed a small management team consisting of one deputy and one assistant head.
Her workload looks formidable, as each school operates with separate budgets, governing bodies, admissions, Ofsted and fundraising.
But she insists the arrangement is far easier than when she was head of just one school. "It may not seem like it, but with this system there are opportunities to reduce your workload, as it gives you the opportunity to raise the status of other people in your organisation," she said. "The opportunity to create another stratum of management has definitely helped, and I can now focus on key tasks and focus my energies far more."
And she insists that the work involved in running three little schools is not three times the work.
"There is quite a lot of overlap, especially on school improvement issues," she said.