One of the eligibility criteria from the Citizenship Act is (quote from the Act):
Short trips overseas are perfectly fine. But extended travels may trigger scrutiny into your intention to reside, or ties in Australia. This happens much more often now as processing time has rocketed from several months to now 16-21 months. When you get a request from your case officer to provide evidence in this aspect, and you have been away for a long time, it could be difficult to deal with. So my advice is, consider all the pros/cons and then make a wise choice. If you do decide to leave, make sure you will have enough evidence to prove your intention/ties when requested
Here is the relavent guideline for case officers from department's Citizenship Policy. I attached the document below, you can read it for yourself (chapter 7)
Also, you can read the cases appealed to AAT that were refused based on this ground: https://www.austlii.edu.au/databases.html (just search for key words like "Citizenship application", "likely to reside" etc.)
Citizenship Policy - 1-6-16 (1).pdf