I used to use front line collars for fleas and ticks on my Rottweiler he never once had fleas and only had a few ticks when I forgot to put the collar back on after showering him.
I have used frontline plus on my dogs and cats for years and never saw a flea or tick. It works great.Only recently I switched to Advantix because for some reason I would find a tick here and there on Lola only. Not sure why the tick part of the treatment was not working for only one of my dogs, but we had to switch.
I have used Frontline for years on my dogs, and we've never had an issue. I'm also using Advantix on Wally right now because he's having some skin issues.