The reason: Brushes can have a varied lifetime depending on how high quality they are and how often you wash them. Quality brushes that you maintain really well can last for years! You should wash your brushes every day if you use them every day (but if it's once a week you're probably ok!). Here's a good DIY brush cleaner, but we've also found that Johnson's baby shampoo works well too thanks to its gentle formula. Clean brushes will help your other makeup products last longer as well, and your makeup will look better when applied with well-kept tools.
Photo Credit: Getty Images/Steve Wisbauer