Consider further searching before International Application
This is usually the stage where the amounts of money involved are significant. So, it's at this point where things can go badly wrong. "Hidden" prior art that would affect the applicant's ability to achieve registration will usually only reveal itself at least 18 months after the ISR is received. By that time, the applicant may have spent tens of thousands of dollars paying for national phase entry. Here's a flowchart for International Applications. Not only that, but investors may have committed or may be thinking of committing significant sums of money to development and commercialisation.
Sadly, the amount of effort put in by a patent examiner with IP Australia does not offset the risk taken by the applicant. This is not the fault of the examiner or IP Australia. As examiners, they would treat each matter without consideration of the circumstances of the applicant. It is really up to us practitioners to ensure that the applicant is made aware of this imbalance and to suggest appropriate measures. Of course, further searching will cost more. However, it is often the case that the extra cost will justify the added security.
There's really no excuse. There are many specialised service providers capable of performing thorough patent searches.