There are often very good reasons for counsel not to go into too much detail about mitigatory circumstances on a plea. In the busy Magistrates' Court, where dozens of guilty pleas are heard and finalised in the one sitting, there simply isn't the time (and some would say, need) to engage in the sort of extended analysis more common in the higher courts.
But there are also risks in providing insufficient detail to the court, in any jurisdiction. In R v Harris  VCSA 189, the County Court sentencing judge expressed dissatisfaction with a report that was produced indicating that while remanded in custody the appellant had completed the Salvation Army's Positive Lifestyle Program. The report indicated only that the accused had, "been attentive, punctual, [and] willing to put strategies in place to help him deal with problematic behaviour".
That's the problem I have with Port Phillip and people like the Salvation Army. What's involved? Who carries out the course? How detailed are they? What was the accused's response?
The judge's questions went unanswered, and he subsequently referred to the lack of detail in his sentencing remarks. It was advanced on the appeal that the judge had not given appropriate weight to the appellant's completion of the Salvation Army course. The Court of Appeal rejected the argument.
It's fair to say that the work of the Salvation Army is better known in the summary jurisdiction than at the County Court. Many magistrates would probably find further information about the Positive Lifestyle Program unnecessary.
Even so, there's a plethora of non-government agencies, running courses and providing assistance of various kinds. Courts are entitled to disregard assertions of mitigation if not satisfied about what has been done and what it has achieved.