High education spending often fails to translate into better results, primary school leaders have been told as they begin to face up to the most severe cuts in recent memory.
One of Scottish education's most influential figures used the example of Sweden, where international performance has slumped despite generous investment, to argue that other factors - such as good leadership - were crucial.
But headteachers have responded by warning that budget pressures will put the country's education strengths at risk.
Sweden offered a "cautionary tale" for Scotland, former senior chief inspector Graham Donaldson told the annual conference of school leaders' body AHDS in Cumbernauld.
In the space of 25 years, Sweden has lost its status as one of the world's best education systems and since 2000 it has experienced the worst decline of all countries assessed through the Programme for International Student Assessment (Pisa).
Swedish schools now suffered from low morale, serious indiscipline and confusion about what was expected of them, Professor Donaldson said. This was despite high education spending and a system that was decentralised in a similar way to that of Scotland.
Earlier this year, the Organisation for Economic Cooperation and Development (OECD) criticised Sweden's education performance, pointing out that it spent about pound;57,500 more per student than the much-lauded education system of Finland.
"The point about resources is particularly pertinent for us given the cuts already made and in the pipeline," said AHDS general secretary Greg Dempster. "However, while it is undoubtedly true that there is more to a high-performing education system than resources, it is also true that a system cannot perform without adequate resources.
"The coherence or consensus about the direction of travel for Scottish education, and how it should be delivered, will be severely tested in the coming period."
Local authority bosses used recent submissions to the Scottish Parliament's Education and Culture Committee to insist that the obvious spending cuts had been all but exhausted.
Education directors' body ADES said in its evidence that the time had come for "system-wide" changes that applied throughout Scotland.
Local authorities umbrella group Cosla indicated that a national agreement to protect teacher numbers would not last beyond this school year.
Professor Donaldson warned school leaders that Sweden was suffering the results of major changes that could be traced back to the 1990s, including a voucher system that ushered in market-driven education, state-funded free schools run by large corporations and an inspection regime whose sole purpose was to ensure that schools complied with the law.
Teaching in Sweden was very individualistic - "Essentially teachers shut the classroom door and get on with it" - and headteachers' jobs generally involved "very little pedagogical leadership", he added.
Professor Donaldson, who wrote the influential 2011 report Teaching Scotland's Future, said that Scotland had a "much more sophisticated" approach to leadership and had become one of the leading countries for self-evaluation in schools.
Former education secretary Michael Russell showed an interest in Sweden's free schools - although that later waned - and during a 2010 visit described what he had seen of the institutions as "very impressive".
He offered encouragement for an East Lothian proposal to establish community-run schools, an idea that did not take off at the time but has resurfaced at recent education conferences.
Earlier this year, the OECD criticised Sweden for spending too much on reducing class sizes. Andreas Schleicher, the OECD official who runs Pisa, suggested that Sweden would be better served by making teaching a more attractive career, as high-performing education systems typically prioritised the quality of teachers and paid them well.
The SNP government initially made reducing class sizes a key manifesto promise. But in recent years, that policy has been sidelined despite unions' insistence that it should continue to be a priority.