There is need and there is performance. I can tell a considerable difference in a shock with 40k miles on it then when new. Need is a realtive term. Id perfer to do them every 25k but the difference for mostly the road , eh , but there is a difference. I do mine about 55k.I had spares in my garage for my 2011. Ended up selling the truck in 2017 at 100k miles for a gen 2…never needed to swap them out.