I had a Cherokee with a landing light in the cowl, and I never flew with the lights on except while landing at night, because I heard that they didn't last long because of the vibration. Supposedly they cost $25 for the cheap replacement or $100 for the better replacement. However, the 75 watt halogens that I have in my wing tips only cost $4. At $4 a shot, I am considering putting an extra taxi light in the cowl. It looks like the best angle that I can get on the wing tip lights will not cover as good as I would like (long ways from flying).
Tracy.