It depends on the type of project. I've backed a number of projects for books by people who do it multiple times and where they clearly assume that most of their income will be the campaign, and that the ongoing sales will be slow, and that rely heavily on cross-promotion with others in the same niche. I think you basically need to set your aims so that it's worth doing for you from Kickstarter alone, and where any breakaway success afterwards is icing on the cake rather than necessary to make it worth your while.