It's not necessarily easy. The timing of Australian elections from issuance of writs is limited by the constitution, and since they can occur at the discretion of the prime minister, you can't prepare for them in advance.

Swiss votes are scheduled in advance, but the explanatory material and campaign flyers still have to be made and in order to be topical you don't want to make them too early. In particular the consequences of previous votes can effect the upcoming votes - e.g. the referendum voted on last Sunday impacts one of the initiatives that will be voted on this June, so nothing could really be prepared until the outcome of the former was known.