Tourist visa extension

Hi guys.
My wife has applied for 309 from overseas a couple month ago. And she is in australia on tourist visa and got 1 year visa validity but visa condition is that she has to leave australia every 3 months of arrival. But visa doesnot have no further stay condition.
Is it possible to apply another tourist visa so that she does not have to leave aus after 3 months?
Will she get visa again similar 1 year time frame or for 3 months only? Is strong reason is needed to show for extension?
Thanks for previous help and expecting this time as well.
Ashish

Strong reason is required. You are probably using visitor Visa for some other purpose and it can be a hindrance in future Visa approvals

Be careful.

Thank you so much Anil.