Nuvu 465 keeps getting me lost

[ltlvt]

This thing is really frustrating me. When on a trip it tells me to take every exit on the interstate and if i don't take it it will go into the recalculate mode. I have taken a new job with a couier service must make several stops in different citys and must be on time. I've had much better luck just driving by the seat of my pants than following the dirrections on this thing. Am I doing something wrong when I set the destination or is this just common with GPS systems? I'm desperate. Thanks