I leave my overdrive active (light off) most of the time. The transmission seems to do a good job of deciding when/if to drop out of overdrive.
Sometimes, I will switch the overdrive off on a long, uphill grade once it has dropped down, just to assure it doesn't start up & down shifting.
Sometimes if I I am on a street with stoplights/stop & go traffic, I will leave overdrive off so that the engine helps slow me down. This is also true of a downhill even on an interstate to keep speed under control without dragging the brakes.
To answer your comment though, the Allison transmission does a very good job of shift control all by itself.