In response to question by Messers Arouet, Aimpoint and Bentleg,
WACs will expire periodically, usually lasting about three years. New charts will be periodically required as although mountains don't move, people do tend to build structures, usually antennas, on the highest of those features in an area, necessitating people who fly planes needing to know about how low they can fly. Info about new ALAs and removed ALAs can also come in useful from time to time, especially if you have an impending mechanical issue, are running out of light/fuel/brains etc...
The following AIC lists the current edition of every WAC and the amendments you should be making by hand to each chart.
http://www.airservicesaustralia.com/...up/s11-h74.pdf
ps. Why the fcuk are people not being educated about this stuff at license level or as a art of their AFR's?