That’s a great question, Vicki.
Initially, there were no limits on how long senators and members could speak. It was thought that they had an important duty to perform and should not be restricted when putting their case to Parliament.
However, in 1918 Senator Albert Gardiner spoke for 12 hours and 40 minutes on the Commonwealth Electoral Bill. This is the longest speech in Australian parliamentary history. It was so long he was occasionally allowed to speak while seated.
Since then there have been specific time limits for speeches. Most debates now have a list of speakers and members of Parliament generally get one opportunity to make a 15 to 20 minute speech at each stage of a bill. There are different time limits for asking and answering questions and for making statements.
All of these time limits are listed in the Standing Orders—the rules of the House of Representatives and the Senate. They are designed so that meetings of Parliament can be run in an ordered and timely way.