I've noticed Waze (owned by Google) sometimes suggests a route I don't feel like (eg I'm on the highway and not in a rush so I don't feel like taking an exit Waze suggests), but when I ignore it and it recalculates, the estimated time goes down.

On the one hand, I know that it has to explore the alternative routes from time to time to know which ones are fastest and that if it's directing a sufficient portion of the overall flow, it has to use multiple routes or else any single route it suggests will become bogged down with too much traffic, but I gotta wonder if there's other motivations, especially when it's a highway exit.