Depends more on what groups you are in (kitten, adult, alter, HHP). If you have cats in different rings, you won't get to watch them all and you will have to keep on top of who's calling for who (judging/finals).
If you have them in the same class (both alters) its a lot easier to do by yourself; otherwise you need a helper.
If you have them in the same class (both alters) its a lot easier to do by yourself; otherwise you need a helper.