Leaders want to avoid "naive promises" for a sprawling city as the federal government kicks in millions to untangle urban developers from red tape.
Prime Minister Anthony Albanese, Opposition Leader Angus Taylor and NSW Premier Chris Minns were among those descending on Western Sydney International Airport's baggage hall on Friday for the Future Western Sydney event.
The airport's first passengers are expected to touch down in October.
It is positioned as the centrepiece of the state's grand plans for a swelling western Sydney, which consultancy firm KPMG estimates will absorb more than 71,000 new residents every year and account for two-thirds of the city's total growth to 2035.
State and federal governments have scrambled to meet the expansion, with NSW set to splurge more than $31 billion on schools, freeways and metro lines in the region over the next four years.
But overzealous development without an eye for the bottom line threatens to leave Sydneysiders stuck in a cul-de-sac, according to Mr Minns.
"We need to be somewhat wary of undoubtedly well-meaning, but sometimes naive promises made about new projects," he said.
He argued for prudence, citing the pressures of rising inflation, interest rates and fuel prices.
"You're not being a killjoy or a party pooper when you ask these fundamental questions," he said.
Planning tunnel vision also means important support infrastructure risks being neglected amid the frenzy, Business Western Sydney chief executive David Borger told the forum.
The region needed more tourism infrastructure to entice visitors, he said.
"I don't think we're ready for it," Mr Borger said.
"We're seeing big international (hotel) brands ... being held up in the bowels of some local councils for years at a time, and we can't afford to do that."
The prime minister announced the federal government was chipping in $72.5 million to help speed up zoning and planning reforms in NSW.
The money will be injected through the federal government's productivity fund, which rewards state and territory governments for "good behaviour" on housing policy.
The premier affirmed any changes would be dished out judiciously to shield some communities from the ravages of rampant development.
"We did it to give these communities, particularly in western Sydney, a chance to breathe," he said.
Nevertheless, Mr Minns said he'd rather a project be over budget than over time.
Western Sydney Interational Airport is set to open on schedule, having finally been green-lit in 2017 after decades of dithering from the 1980s.
