My plug to echo M.F. - we have used no pesticides on Poppy at all this year, since she has had really bad reactions to both Bravecto AND to the Scalibor collar. Yes, she picks up the odd tick - but that happened using the pesticides as well. So far, we have been amazed how well this is working. She is sooooo much happier this year - last year she had a cluster of fits a week after we fitted her with the Scalibor collar, but then she seemed to settle down with it. However, she was very upset by the heat, and was quite depressed all summer, really quite down. We thought it was just the heat, but I suddenly realized this week that despite it being every bit as hot this summer, that she has been so much better, not depressed at all. In retrospect, both I and OH are certain this is due to the lack of flea/tick treatments.
Every dog is different, and we do use the Scalibor collar on Merlin during the high tick season, as he seems to tolerate it very well. I never bother otherwise about flea treatment and would just treat any infestation as and when it came up (none of my dogs has had fleas). It is a balancing act and not an easy decision to make, I think. It's important to weigh up your circumstances, where you live, and your dog's health.