Tft "navigation"

Out of curiosity i tried out the turn by turn navigation again to see if it was any use.Put in my home address when I was over in Johnstone, just outside Paisley .Up popped the wee arrow, indicating a right turn 600yards ahead. I thought bugger that ,I will continue straight ahead and stay on the main road,much easier route and miss out the damp ,leaf strewn route the navigation picked out.i was expecting the navigation to change route,but it stuck on 0 yards as i passed the turn and stayed there till I got home !! Wtf is the point of it,surely the money spent "developing " that ,could have been put to better use.