[msingle]

What are you talking about? I found https://en.wikipedia.org/wiki/1975_Australian_constitutional.... But this looks like political maneuvering between parties more than the queen being arbitrary (or using powers that normally can't be invoked.

[midislack]

To understand just one of the Monarch's many powers as the representative of the Crown, you should read the essay entitled The Royal Power Of Dissolution. There is no "normal" limit, the Monarch, acting on behalf of the Crown, is Sovereign.