@chris First past the post systems are designed to establish a two party state. The only sustainable winning strategy is to unite one half of the electorate.
Hubris for the party that believes otherwise.
Tactical voting (eg ABC) is unpredictable and unsustainable. Likewise voter suppression and dividing your opposition.
First past the post is only one better than a one-party state, which is why so few democracies still use it.