I have never used a flea treatment on Coco - she has garlic in her food and I think that helps a lot - she has never had fleas or a tick.
Having said that I don't think ticks are particularly prevalent where I am as I have only seen a couple on one of my cats in 2 years
I prefer only to treat if I see a flea and ticks I would just pull out as and when. Not sure what I would do in a highly infested area though but garlic in the food might do some good.