Depending on the texture of the fur and how much the coat mats you would be grooming once a day or a few times a week. The silkier the coat, the less grooming but on a longhair its at least 2-3 times a week. If the coat is like a persian or mats easily - you need to comb every day.
I have shorthair cats - they get petted mainly for grooming but will run the flea comb thru the coat a few times a month - a little more often when shedding season. Ling needs it more then Charlie, as his coat is fine and rarely needs any kind of grooming.