The Gsync pendulum demo is just like a game, so is Windmill demo, etc. Even many desktop apps that you may think oh that's just some Win32 windowed app are in fact using a more modern API and actually run HW accelerated via GPU with adaptive sync active (windowed mode), etc.
Either adaptive sync is active or not, there is no "in between" or "something is wrong with the app" XD
If you get occasional tearing then the output is going out of adaptive sync range too much. Overdrive wise... good luck seeing that in games that have enforced motion blur. Games with very variable output/frame pacing are gonna suck no matter what.