I guess our experiences vary - our family had month long adventure vacations most years since the 1970s, and growing up we did a half year tour about the whole country when dad got cumulative long service year.

Some employers "force" their employees to use a portion of their annual leave during the Christmas / New Year shutdown period (usually 24 December -> first full week after New Years Day, if not longer). So you might not be able to use the full 4 weeks continuously.

This can be an unwelcome feature for some people, for example, if you want to have a vacation in the northern hemisphere summer season instead and/or maybe you don't have substantial family in Australia (or at least, those you actually want to see).

The auscorp reddit has a yearly thread on this issue: https://www.reddit.com/r/auscorp/comments/1mw6pqt/end_of_yea...

Those with school aged children might also want to save some of their annual for the mid-term/mid-year breaks as well. (Our academic years are aligned to calendar years)

Likely varies by industry - a peer Australian (probably in private IT ?) stated it's uncommon to take a break, whereas I'd say in mining, oil, gas, civil service, police and a good number of structured contract employment its more common.

I've "retired" into agriculture and a lot of farmers take a month off after harvest time to go fishing or other wise relax (this generally means filling up a couple of deep chest freezers with fish for the rest of the year).

In Germany your employer has to grant you two consecutive weeks of vacation by law, and vacation is very rarely denied, even for 3–4 weeks breaks.