As a Nexus owner, I know every month that Google is going to release a security and bug fix update for Android Marshmallow my Nexus 6 and Nexus 7. The challenge of course is when that update will actually hit my device after it has been released. Google, like other manufactures, stage these updates and it can sometimes take weeks for it to hit your device.
Don’t get me started on carrier locked versions. -.-
While you can always manually check to see if the latest version of Marshmallow on your device (Settings>About Phone (or Tablet)>System Update), the reality is that really doesn’t get you moved up in the queue any faster and some have suggested it makes no difference at all.
There is however a way to force an update to your device by manipulating the Google Services Framework on your device. Indeed it is quite possible that this method will work on non-Nexus devices but I have not tested it. The key thing for you to keep in mind as you try this is that it may take you several attempts to get this to work – and it may not work at all. In my case, it took me 1 try to get my Nexus 7 (2013) to update to the January build of Marshmallow but it took me no less than 6 tries to get my Nexus 6 to update to the same release. Patience is important but this could be a way to get an update a bit quicker other than a full-on flashing of the device. Also, do this at your own risk as you are manipulating how Android operates on your device. You may have to restart your device and worst case reset it.