Seeing as the OP asked a specific question ("How often..." etc):
Since we moved into our house on the outskirts of Sydney (North Rocks) just over 3 years ago, I reckon we've had:
5 or 6 Huntsmen
4 or 5 female Redbacks plus a couple of males
2 Funnelwebs, 1 of which had about 200 babies crawling all over its back
That's obviously not including the dozens of "normal" house / garden spiders etc.
It's just a fact of life, really, and the only difference between the ones here and in England is that some of them here are poisonous, bigger, and run like they've got jet propulsion on 'em.
