Remember, we now have better quality steel and barrels than ever before. With this quality comes better life span of the barrel.
Keep your loads at a reasonable speed/pressure and the barrel will last a very long time. Load hot snot speedsters at max or over consistantly and you'll wear out the barrel sooner rather than later. Also, as a gentleman stated earlier in this post that excessive heat is the evil of barrel life. Very true, so, shoot a few, let it cool a bit, shoot a few and so on....
I'd rather be the most accurate guy on the range than the fastest bullet there!!!