Can you do insurance for 6 months?

As long as you pay for both the CTP Insurance and registration within 21 days of the due date, you can choose a 6 month term for the renewal of your CTP.

https://www.aami.com.au/faq/can-i-renew-my-nsw-ctp-insurance-term-to-6-months.html#:~:text=As%20long%20as%20you%20pay,the%20renewal%20of%20your%20CTP.