I wonder how much time it really saves you, too. My experience with all sorts of apps like this (including Waze, although I haven't used it in a couple of years) is that they tend to underestimate the speed of heavy traffic, and overestimate speeds of small streets. They especially seem to discount or even completely ignore the potentially large time costs that come from stoplights, stop signs, and left turns.

These days, if my system has me get off the main road, take small streets for a while, then get back on the main road, I'll ignore it unless the traffic it shows is really, really bad. Occasionally I regret this, but I regret it less often than I regretted obeying the machine before.