I treat my front and back yard and also my carpet in my house with growth regulator once a year. This almost always takes care of the fleas. My yard gets soaked for days over a heavy rain. Before without treating the yard I would bring in fleas just by cutting the grass when I had no dog.
I don't use frontline unless the growth regulator doesn't work, but really if you do it right it will always work. Frontline is the same thing except you just put it on animals.