don't worry about it. Each barrel/load combination is different and if you maintain the barrel well.
It will last a long time, shoot it and enjoy it until it happens and even then the barrel it's self will not be gone. Only the throat, and setting the shoulder back will normally bring it back to life.
The most harm comes from firing it to fast and not allowing the barrel time to cool off. The big magnums with lots of powder generate lots of heat and 2 or 3 shots in quick succession can exceed the recommended temperature for longer barrel life.
J e custom