Key findings are that in some secondaries give pupils over an hour a week more teaching than other schools, classrooms in some schools are used twice as much as those in similar secondaries, and large schools are not necessarily more efficient spenders.
Adapting a system called "benchmarking", applied in most further education colleges, the survey also underlines the high cost of teaching small classes in fifth and sixth years, a particularly significant discovery with Higher Still due to begin in under two years.
Mike McCabe, director of education, described benchmarking as the "missing management tool" which explains in minute detail how heads spend their #163;2 million budgets. He accepts the findings are "sensitive".
A software package devised by Ben Johnson-Hill Associates, a small Nottingham company, allows consultants to compare spending in each school against the average for the council. Five key areas have come under scrutiny: teaching, academic support, administration, premises and catering.
One of the most surprising findings is that in an average size school of 900 pupils with a #163;2 million budget, teaching costs can vary by #163;325,000 because of astute decisions on timetabling, class organisation and absence cover.
Mr McCabe explained: "It's not money you can make a saving on but you could do more with your resources. If, for example, you move onto the S5 timetable two weeks early, it will change the unit cost per pupil. How you plan your year and your classes is critical. Timetablers need to know the financial implications of their decisions".
He added: "We recognise there will be differences between schools but these should be by design, rather than omission or chance. Benchmarking is one tool in the tool box, but it's the tool that's been missing".
Pupil contact time varied considerably. In one school, pupils had 910 hours of teaching during the year in contrast to 975 in another, a difference of over an hour a week. Christine Pryce, head of resource development, said there was little difference between first and fourth years but substantial variations in the senior school. Schools with larger numbers doing sixth-year studies, including more self-study, could account for some of the difference.
The survey also shows classrooms in one school were used over five hours a day but under 2.5 hours in another, a 50 per cent variation. Mr McCabe said: "That's critical information authorities need in terms of knowing where school accommodation is under pressure. An authority cannot demonstrate best value unless they can answer the questions about how they use the resources they have available, either buildings or personnel".
The council has asked heads to look at their performance against the average and is considering relaxing its devolved management scheme to allow more financial freedom in schools. Nine primaries are now involved in a further pilot.
Ian McEwan, head of Queen Margaret Academy, Ayr, welcomed the information as an aid to the school development plan. "It focuses the minds of people in the school to alternatives to present practice," he said.
The findings showed average class sizes at the 700-pupil secondary to be 0.8 above the council average. Senior managers therefore cut the number of S2 classes this session from five to four, raising classes from 23 to 28 pupils. It represented a saving of #163;17,000 in staff costs but allowed the school to introduce co-operative teaching in S1 and S2 and refocus on the upper school curriculum.