My GPS has been acting stupid lately. In Albuquerque recently I programmed in the Flying J just a few miles away but it took my like 12 miles around a loop with every light turning red. I was mad, but more at myself for getting off the freeway blindly following my GPS suggestions. In Dallas, leaving the truck stop to go pick up my load which was to the west, GPS says get on the freeway going east take the next exit 4 miles up and go back west. Why do I want to do that when the westbound onramp is 200 feet beyond the eastbound one? I think what happens is that it 'sees' the first road that will get you there and doesn't necessarily see the bigger picture.
uncannily, every time i blindly follow my gps it is wrong. when i am thinking straight, i will program the route, then go over it with a fine tooth comb. after verifying and fixing all the little gps glitches, i will write down the resulting directions on a post-it and stick that to my steering wheel. now, i have solid written directions, and then use the gps as a moving map to see how close i am to the next maneuver. it takes a few more minutes that way, but by the time i am done i have practically memorized the destination and it makes me feel a lot more confident about getting there. this method has saved me from a lot of bad mac 23 directions.
