Originally Posted by
mibike
Don't use Route navigation on an eTrex. If you do and you get off course for any reason it will recalculate the route. When you get back on route it will recalculate again and most likely will be different than the correct one.
It has been awhile since I used an eTrex but you might want to look for the ability to turn-off auto re-routing. I has been an option for as long as I can remember on my Garmin Edge units.