In reviewing the $16.2 billion scheme that delivered more than 2000 halls and libraries and other buildings to schools, a taskforce found the Curran hall cost $380,000 more than it should have, and pronounced it "not value for money" in stark red pen.

That was just one of the projects highlighted by post-mortems which found that the school building program helped insulate Australia from the GFC but cost much more than it should have, especially in NSW.

This was the kind of thing Morrison was so determined to avoid in his coronavirus stimulus.

He didn't want government schemes like Kevin Rudd's school hall and home insulation schemes.

He wanted business-led programs - tax incentives for equipment and wages, subsidies for apprentices, grants, loan guarantees, and finally his wage subsidy, also delivered via employers.

Now he is set to announce stimulus mark 4, and this time, he's turning the focus away from broadbrush schemes to specific industries.

Construction is expected to be hit hard by the pause in overseas migration and the fall in house prices.

Treasurer Josh Frydenberg says dwelling investment will fall about 20 per cent in the June quarter, and price data this week showed prices are once again on the way down.

Construction employs more than one million people, and home building is worth $100 billion to the economy, Frydenberg said, pointing to a long supply chain, "not just the sparky and the plumber and the carpenter ... also the timber mill [and] the appliance manufacturer for the new kitchen."

The government has not given details of it plans, but reports this week suggested it will offer cash grants for home renovations and extend first-home buyer's grants to people who already own homes, encouraging people to spend money on new builds.

Morrison has already found that it is more difficult than he might wish to avoid the pitfalls of quickly conceived schemes.

An audit highlighted the massive task faced by education authorities trying to build more than 2000 halls and libraries quick smart, in just a third of the time normally set aside for school infrastructure, and commented: "Implementation issues were more likely to arise due to the limited time available for policy development and program planning."

Anyone who has watched the stimulus roll out since March can easily nod in recognition - JobKeeper has faced myriad complications small and large, JobSeeker was floored by its early oversubscription, the superannuation scheme has been the target of fraudsters, is seeing people draining savings for reportedly unwise spending and needs careful handling to ensure the liquidity of superannuation funds is not threatened if claims spiral.

This is the context in which Morrison and Frydenberg turn to specific industries.

The government's game plan appears to be to keep tradies working and supply chains flowing, and if that's the aim then injecting cash could achieve it.

But it must be alert to the danger in any hastily put-together grants program of fraud, manipulation and market distortion (who will now sign a home renovation project today or any day in the coming weeks until the anticipated scheme begins?) and it must also consider wider consequences.

Housing affordability was the great challenge just a few short months ago and remains in the background as an intractable problem.

The Reserve Bank commented some years ago in relation to the first home owners grant that "policies that simply give people more money to spend on housing are likely to be capitalised into higher housing prices".

It's fair to say that the government is probably not overly worried about affordability just now and is more interested in keeping house prices stable (it has, after all, just introduced a scheme that allows first home buyers to buy a home with 5 per cent deposit), but intervention in this market has a history of skewed outcomes.

In short, housing is an industry that has proven itself singularly difficult to balance.