IMO if you are happy with your results (you have your pit dialed in) and you are getting enough product on each cook, you run that sucker until it falls apart. That is, of course, unless you just NEED a new cooker, then you go get what you NEED.
Weber 26.75 OTG w/CI grates & SJ/WSM Mini
Home built 24"x72" reverse flow stick burner trailer with 18"x40" grill w/CI grates and upright SS gas oven/smoker.
Home built 48" fire pit with a 30"x30" Santa Maria style ranch grill.
Home built lump charcoal retort, iGrill & a bunch of other cooking toys.