score:6
Let's take a look at why did the PMs leave the first time this happened:
From this, we can deduce following factors:
So basically it all goes back to the Federal Elections of 1903. Protectionists formed the government but as they lacked majority, they had to rely on support of Labour. The alliance of Protectionists and Labour was very fragile and soon fell apart, when Deakin proved unable/unwilling to meet Labour's demands on Conciliations and Arbitration Bill. Labour as a result withdrew their support and Government fell. George Reid refused the offer to form Government so Watson was invited to do so. Watson found it easier to resign than rule as he had no majority. Reid then formed government but it did not last long as Labour and Protectionists reconciled and ousted Reid.
The Federal Elections of 1906 also generated similar results of no party gaining simple majority. Deakin once again formed a minority government but was ousted after losing Labour support. So Andrew Fisher formed the Government. But then Protectionists and Free Traders joined to form Commonwealth Liberal Party, therefore gaining majority. Fisher was voted out by newly formed CLP members. Alfred Deakin once again became PM.
In Federal Elections 1910, Fisher finally won majority. He remained in Power until Elections of 1913 when CLP under Joseph Cooke won by a narrow majority of one seat.
Since in Australia there is no term limit on PM, we have to rely on Election timing. Elections usually occur in 3 years in Australia but they can be held earlier if the House is dissolved.