Defence Minister Peter Dutton confirmed 103 people had been rescued by ADF helicopters since the flood crisis began.
But personnel are stretched over a geographically huge area spanning the south-east corner of Queensland and down the east coast toward western Sydney, he said.
"The effort on the ground is frustrated in some areas because it is inaccessible even to the ADF with their vehicles to get in and start the clean up," he told the Nine Network on Friday.
"There is a sense of reassurance when the ADF rolls into those streets, and they know that ... they understand the gravity they bring to a local area to boost spirits and to help people get back on their feet."
The Commonwealth is working with Queensland to deliver further support to flood-affected areas, asking the state government for a list of projects where funding is required to rebuild.
It comes as the federal government announced a joint $435 million support package with NSW on Thursday, with a second package in the works.
The package includes grants of up to $75,000 for primary producers and up to $50,000 for small businesses and not-for-profit organisations.
Large parts of Queensland and NSW remain underwater after heavy rain and flash flooding over the preceding days.
South-east Queensland remains on alert for life-threatening floods from dangerous thunderstorms after deluges killed nine people and damaged over 17,000 properties in the state.
In NSW, Greater Sydney, the Central Coast, South Coast and the Hunter region also remain on alert for more flooding.
The clean-up continues on the state's north coast in cities like Lismore, which was hit by the region's worst floods on record.
Shortages of critical supplies like food, fuel and fresh water also remain.
Supply chain problems caused by rising water blocking critical road and rail links led to the prime minister convening a roundtable with key ministers and officials on Thursday.
Defence chief Angus Campbell, Emergency Management Minister Bridget McKenzie and disaster assistance coordinator Joe Buffone attended.
Since the flooding, $62.7 million in disaster recovery payments have been provided in relation to 52,000 claims lodged with the federal government.
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