springs can vary a bit batch to batch , some small difference in manufacture makes some types vary a lot. the heat generated by shooting the glock is a lot more than any heat from our weather. should you change the spring at 5,000 rounds ??? well if it having problems cycling yes on question, if it is not having any problems , me , I would change it anyway being proactive , the springs are cheap enough, and I would rather have total confidence in the gun.