A while back Glock released a Wearable Parts Replacement Schedule to LE armorers for .40 models used by LE. It's a suggested replacement schedule for non-warranty "wearable" parts that can wear out over time in normal use and such wear is not considered a warranty issue.
In the G23/23RTF models (Gen3 & earlier) the following parts were listed for replacement as follows:
Recoil Spring Assembly - 2,000 rounds
Magazine Spring - 2,000 rounds
Firing Pin Safety - 5,000 rounds
Firing Pin Safety Spring - 5,000 rounds
Slide Lock - 5,000 rounds
Trigger Spring (coil) - 5,000 rounds
Locking Block pin - 5,000 rounds
Now, they also included a recommendation that the recoil spring assembly should be tested at each range session or qualification, using the standard Glock recoil spring field test as taught in the armorer class, and to replace the assembly more often as may be needed.
Also, they recommend that for best results the mag springs should be changed at least every other time the recoil spring assembly is replaced.
After the list was sent out I was later told that Glock now considers their current trigger coil spring spring (light gray color) to be a lifetime spring (unless they change their mind sometime or find a better one).
In my last Glock class it was repeatedly mentioned that if we're seeing broken locking blocks, locking block pins & trigger pins that we aren't replacing the recoil springs often enough.
Locking block pins have been revised at least once that I can remember, and I was told that the change involved how they were hardened.
I was exchanging some info with another LE Glock armorer online some time ago. He told me that they had experienced some broken barrel lugs (forward lugs) on their G23's. If I recall right, their guns were about 10 years old and had apparently never had their recoil springs replaced. Well, battering isn't a good thing as a recoil spring ages and becomes weaker. The stress is going to be transferred to the gun.
The new Gen4 recoil springs for the .40's are expected to last longer, 5,000 - 7,000 rounds from what I was last told.