I actually do NOT generally recommend that you stick to a single range. I absolutely believe in “cherry picking”, the best products out of the various ranges to create the best skin care regime for you. As long as the product choices that you are making are benefitting your skin and giving you good results, that is absolutely the way to go. It’s about getting the active ingredients that your skin needs to give you the desired results. So by all means, as long as you are using good quality products with good actives and they are working for you, you mix and match what works!