I can long periods with no changes in my system. Sometimes a component fails and I need an alternative for a period of time. Then the merry-go-round starts and I read everything that I can to make a considered choice. I typically buy quality used gear to stretch my $.
sometimes a "wishlist" component shows up and I buy it to try it out. Over time, I end up changing just about everything but my speakers (too large and heavy to bother with changing out.)