You need to be mindful how Frontline actually works. The product is in no way a repellent, it just kills fleas, lice and ticks. Fleas are good and easy to kill because they move about and pick up a large dose from the grease on the hairs. Ticks crawl to the skin, embed and feed. There is less opportunity for them to pick up a large dose so as to kill them quickly (especially once the Frontline has been on a couple of weeks).
What the Frontline does is kill the tick very effectively within 48 hours. Why is this important? Well for the tick to transmit vector born disease (Lyme disease etc) then the tick has to be attached (and alive!) for 48 hours or more. Merial pretty much guarantee the product will effectively kill ticks for a month after application.
If you expect not to see ticks on a dog treated with Frontline you just don't realise how it works. But they die before they cause a problem.
This is why I like the Scalibor collar - these actually repel them.
I thought that was the case Apache.
I apply it every 4 weeks but miss a dose when I start picking up less on myself and seeing less on the deer - is it adviseable to give the dogs a break from it?