Lessons must be learned from the early mistakes in a £45bn school rebuilding programme, the government has said.
The DfES says it is getting plans back on track
The flagship project to rebuild or refurbish all of England's secondary schools by 2020 has been hit by delays and a lack of expertise.
Building Schools for the Future (BSF) would only be a success if we "learn from what's already working", Schools Minister Jim Knight said.
The Number 10 delivery unit has stepped in to get the project back on track.
Some 72 local authorities are involved in BSF projects waves one to six which aim to rebuild or refurbish 1,000 schools.
But only five local authorities have reached the position where they can start building.
Speaking to a meeting in London of 15 local authorities who have successfully bid for new investment under the programme, Mr Knight said: "I make no apologies for making sure we get this right, because these schools must be built to last.
"The process of planning, financing, designing and building is complex and can't be completed overnight - it will take time.
"But it will be done. Already across our capital programmes, PFI contracts have been signed covering more than 800 new build or refurbished schools.
"More schools have been built in the past five years than in the past 25."
He said decaying classrooms had been removed and leaking roofs repaired.
But he added: "This programme will only be a success of we really learn from what's already working.
"We must be smarter about sharing experience. And local authorities must have the help they need to deliver the projects.
"The first few waves have also shown the importance of securing quality through fit-for-purpose design and making sure that school leaders have the skills involved."
A DfES spokesman said it was now acknowledged that local authorities in the first three waves of the BSF programmes had lacked the management expertise and capacity to oversee such massive projects.
Since then, he said, there had been major changes to the way the programme was overseen and organised.
Now only local authorities who could show they were ready and able to proceed with large-scale building programmes were eligible for funds.
He said: "We are saying you are here because you have shown you are ready to take on such a project and you have the expertise."
More help is now on offer to school head teachers and local authorities to ensure schools are well designed and match the needs of the future, he added.
Earlier this week the Conservatives claimed millions of pounds ear-marked for school building projects had not made it through to the front line.
They said projects were delayed, with only 14 schools due to open by the end of the year instead of the 100, they claimed, were originally intended.
Last month government officials overseeing the programme acknowledged the delays and told MPs there was risk it would be damaged by a lack of expertise.
Sally Brooks, who manages schools capital for the Department for Education and Skills, said the programme had "slipped" from its "very ambitious timescale".
She also said there were fundamental difficulties with the way the project was designed to be managed by schools and local authorities - albeit with assistance from Partnership for Schools.
Director of the British Council for School Environments Ty Goddard said he was looking forward to see the findings of the prime minister's delivery unit internal review. He added: "We must acknowledge, however, that the current BSF process doesn't play to the strengths of our world class architects and builders, which means we can end up with the wrong kind of buildings."