I've noticed from what I've been reading here and AnandTech articles that the disparity between different user's SOT has to do 3 things: the kind of use each one has, the SOC, which can be slightly different in each smartphone, and the battery itself, which can also have differences. Otherwise, how could you explain me not never ever getting mere than 3,5h SOT on my m8, which I bought back in August 2014? Maybe if I change my battery things get better. I have to charge it twice a day now. I'm a heavy user and use 4g mobile date only, with auto brightness with the slider to the right, gps on exact location and Bluetooth always on, connected to my Moto 360.