well my Lumia 1520 has been great on 10586.11 , the battery in my case has improved, I get all day use and still get 40-45 percent remaining, messaging right as I type this has only used abt %6.7 , lock screen is %1.4 only I keep glance screen active all the time. I am kind of a person who keeps everything running , location, wifi, brightness on auto, all apps allowed for notifications....im pretty amazed and satisfied with the battery life, as compared to older builds. btw mine is RM-937, didn't do a hard reset since 10572.