To some extent, each brush may need to be cleaned a little more (or a little less) than the other. For example, if you use lip brushes to apply your lipstick and glosses, you’ll probably want to clean them more often. Mainly because you change your lipsticks a bit more than any other beauty product (at least we would assume so).
But really, the best way to determine when you should clean your makeup brushes is by looking at the amount of buildup in the brushes. If your brushes are starting to show makeup (especially foundation and concealers and blushes) in the bristles, it’s time to clean them. If you still can’t make an educated guess on that alone, we’d say go for a cleansing every Sunday, just to be safe.