It depends on your TV model. Some TV's would end up with a blurry Image when using 0 and some models would end up very sharp with a hollow effect around the edges with anything above 0. And some have 50 set as a baseline. So regarding the newer Samsung models 0 Is what's mainly used by professional calibrators on AVS forums, Even Digital Foundry recommends 0. http://www.rtings.com/tv/reviews/samsung/ks8000/settings Calibration settings for KS9800 with sharpness set to zero. http://www.avsforum.com/forum/attachment.php?attachmentid=1620897&d=1472060861 You could always test for your self with a proper sharpness pattern from a generator and/or calibration disc. And yes you are correct It's always better to calibrate each TV separately since panels differ slightly and colors tend to shift over time. Therefore It's always best to calibrate every 4 months to maintain optimal colors at all times.