This time length shouldn't compromise most investigations. It would raise awareness to over reach, so if a small handful get this it's probably well focused but if ~5% of the country start getting letters, people realise the overreach, it will become discussed and create push back politically.
Shining light on things is often the best solution to government issues.
2) Secondly, I'm seeing strange commentary on this thread and other locations a heap about Australian repression and tyranny type comments. And while there are privacy issues and there has been police overreach in the protests/quarrantine, comments seem way off the mark. I'm not sure if it bots/paid players trying to drive agenda or really skewed views. Some of the language is very properganda like and I've seen many posts on other platforms showing things out date or context clearly aimed to drive emotion. So I'd say fact check and consider context before getting too worked up about Australian issues of late. It's still a great country and not the run for the hills situation some people seem to be pushing.