...except that that's the important bit. The incentives in the short term are fairly small, but the compounding really starts to kick in later on. After 5 years, if you can maintain your "top dog" raises, your salary will be just 15% greater than the bench-warmer's, and after 10 years it'll be about a third greater. However, at 14 years you're earning a full 50% more than them, and at 25 years you've doubled your salary compared with them.

I say "compared with them", but it's more "compared with yourself under different circumstances". I'd say retiring at a salary more than double what it could be is worth the extra bit of effort, and let's not forget that salaries are often part of a grading structure, so your higher retirement salary may well also come with other benefits commensurate with higher grades.