Staying is an awful plan right up until the point where it isn't. That point depends on local factors like which roads you can take. If there is only one access road and it's in the fires path with no time to escape then you're better off taking your chances at home with a garden hose or swimming pool. A significant number of the black Saturday deaths were from people that left evacuation too late: https://en.m.wikipedia.org/wiki/Black_Saturday_bushfires