What these breeds have in common
The longhaired cats are the ones that genuinely need a professional, and the group most likely to be left until it is a problem. Persians, Maine Coons, Ragdolls, Norwegian Forest Cats, Siberians, Birmans, Himalayans and Turkish Angoras.
The coats vary more than they look. A Persian carries a fine silky coat with very little undercoat that grows continuously. A Maine Coon or a Norwegian Forest Cat carries a genuine double coat with a dense insulating layer underneath. Both mat, for different reasons and in slightly different ways, and neither should be approached with scissors.
The thing that catches everybody is that these cats look immaculate right up until they do not.
What this group means for grooming
The cats that genuinely need professional grooming. Mats form against the skin under the armpits and behind the ears where an owner never looks.
What actually decides the grooming
The coat type, not the group. It sets the tools, the interval and the price, and two dogs in this group can need completely different appointments.