I've been flying almost 10 years and can probably count on one hand where the route has changed due to turbulence. For shorter domestic flights it really doesn't make sense. Altitude changes will make a difference though. Once we get to cruising altitude, usually ATC will advise how the rides are based on earlier reports. They'll also suggest smoother altitudes if they know of any. Overseas flights will change flight paths though, but probably more because of winds.