I'm ashamed to admit this, but my second 240D, an '84 Euro model, went several hundred thousand miles without every pulling the valve cover. When I finally got a wild hair one day and decided to check them, they were not far off at all.

Unless you are not changing oil very often or have some reason to believe that the valves are not staying set as well as they should, I think 15,000 miles is overkill.

I have been criticized and even TORMENTED for my frequent, hot overnight drain oil change regimen, but I think that it was at least partially responsible for my lack of valve train wear.