You certainly dont need to do it every week! If you get one from your local vet (Acclaim is very good or you can buy one called Zodiac from Pets at Home) follow the directions carefully (its very simple to use but make sure you tie a damp cloth around your face, the spray is very toxic). One spray treatment for the whole house will keep you protected from all fleas for up to one year. Its not worth messing around with the cheaper products bought from pet shops and supermarkets. They dont work efficiently. Best of Luck.