that's an awful long time. probably a good idea to change them sooner than 4 years. i'll say this as a hunter and not a string maker - when i go to hunt deer out of town for a week, i've got a backup set already shot in, dialed in, and withserving for the drop-away installed ina baggy with the loops tied together so they won't twist or untwist. in case i have an accident at camp or in the woods - 5 minutes on a portable press and i'm up and running again instead of scrambling to the nearest shop and hoping they have a set for my bow. i get a lot of emergency calls in season - and that is not the time to be calling with an emergency - because it seems everyone is having one.