Headteachers in rural parts of the Highlands could be put in charge of up to six primary schools under proposals designed to help save millions of pounds.
Heads already manage two - sometimes three - schools in some areas. The bid to go beyond that is part of Highland Council's budget consultation on saving pound;30 million over the next two years.
The Association of Headteachers and Deputes in Scotland (AHDS) has warned, however, that joint headships do not necessarily save money.
Dave Fallows, chairman of Highland's finance committee, has said he will be talking "very closely" to teachers about a proposal that some heads cover four to six primaries.
Greg Dempster, AHDS general secretary, said: "While there has been a growing trend in Scotland for headteachers to be asked to look after more than one school, it seems to us that this proposal would be a step too far.
"The suggestion that a headteacher could effectively engage with, lead and develop four or more schools under a model similar to existing joint headships seems flawed on a number of levels."
AHDS is not opposed to joint headships in principle, and accepts that they are a way of keeping open schools with shrinking rolls. But it insists that, if the roll subsequently grows, the school must regain a headteacher of its own. Mr Dempster added that a joint headship might not always generate savings, as there could be a need to appoint additional promoted posts in each school to ensure someone was available in the event of an emergency.
"Such a model as Highland is now proposing would certainly require such an arrangement," he said. "One member summed up her experience of heading up two schools as: `It doesn't matter which school you are in, it is always the wrong one.'"
Work-life balance was also an issue for heads serving more than one community, Mr Dempster added.
Andrew Stewart, Highland EIS secretary, said that the union preferred to see a headteacher for each school, but had in the past reluctantly accepted pragmatic reasons for a head managing two schools when recruitment had been problematic.
Asking a head to manage as many as six schools would be "crazy", given the distances involved, and not as efficient as it looked, since each school would still demand individual paperwork and planning.
Highland Council is also exploring the idea of reducing the school week by two-and-a-half hours - equivalent to teachers' non-contact or "McCrone" time - for all P4-7 classes, which it believes would save pound;3.2 million a year by reducing the need to employ additional staff to cover those hours.
Nursery provision is in financial officers' sights, too, given that 33 providers operate with six or fewer children.