well kat does well with certain champs, if you have a jax on your team and you see him getting ready to stun their team or even if its not a team fight, that one person. thats a chance to ult, while they're cc'd and cant get away. another thing is to watch their team, know who can and cant stop your ult and try to wait out ultill their cc is used before you go in and try to use your ult. amumu's ult is a nice way to get off a decent kat ult, and so on. if you pick kat you really want to make sure their whole team cant stop or ult or you better have a team that you can rely on to cc so you can ult.