I currently have four brushes that are in my rotation. I have a fifth but it needs a new knot. I’m not sure if I’m going to invest in replacing it and I may just throw it away. It doesn’t have that much of a sentimental value to be honest. That brush is about 30+ years of age and was my primary brush for about eight years before I got additional ones to rotate with.I guess it took a beating and it causes the hairs to become brittle overtime because of lack of reconditioning and rotating it with other brushes. I just recently added a Thater to take its place. All my brushes are natural composite. Badger of some type of configuration to be precise.. I find by rotating my brushes basically will make them last as long as I’m around on the planet.So far this is proving to be true. My next old is brush is a Hans Beiar Badger that’s almost 25 years old and better than the day I received it as a gift.I really haven’t cleaned it much “ other than a sterile rinse and dry” in the past couple years and it still hasn’t lost any hairs. I believe it’s due to the fact that I rotate my brushes on a regular basis. I like to hear some other thoughts on the matter from those who Do the same. It’s been my experience that this has been a combination that has allowed me to have my brushes for a long time without replacing the knots.