The Zoom Groom cleans the undercoat brilliantly--that's why mine and Gizmo's filled up with hair with only a couple of brushes. If you are getting only guard hairs, the cat's undercoat isn't shedding yet.
When Gizmo lost her winter undercoat this Spring, I had to empty the Zoom Groom three times since it was packed with soft fur each time. I wound up with enough felt to make a coaster six inches around and an inch thick!
Gizmo is not shedding as much now so I get mainly guard hairs. After a few brushes most of the hair stays in the Zoom Groom since it is electrostatic action that makes it work. Sort of like rubbing a balloon on a cat's back.
Anyway, some of it does come loose and go towards Gizmo's tail, but I"m no longer wearing a fur coat after I brush her!
You have to brush her more than once a week at first, and the hair sheds will naturally go down.