Visa Canada Immigration

Travel in the Shengen zone?

If I am from a country (Australia) that does not require a visa to travel in the shengen area for less than 90 days, is it possible to travel for 89 days, leave the shengen area for one day and then come back & start my 90 days again? What checks do they do at the airport?

As Australian citizen you can travel 90 days out of each 180 days, so no, you can not leave the Schengen zone for one day and return.

What you can do is travel through the Schengen zone for up to 90 days, leave the area for 90 days somewhere else, like the UK and Ireland, and return for an other 90 days.

Often the check at the airport is not much, but they can want to see your money, (or the proof that you have enough money for the time you want to travel in Europe.)

I have read questions here from people who got in problems because they had planned to travel as I outlined above, (Schengen for 90 days, UK for a while, and back to Schengen,) and were refused entry to either the UK or the Schengen zone, because they were suspected to want to work instead of traveling as tourist.

I think that in the UK you can get a working visa, and maybe for Europe a working holiday visa, but I am not sure about either.
If you are interested in working or working holidays, add to this question or ask again, because there are regular answerers here who are better informed about those.