[Samsung Galaxy S7 Questions and Answers] xxaarraa:
Gents and ladies,

Tmobile SD820 S7 flat user here, and like everyone else, have the high android system battery drain issue I have been trying to hunt down. Till samsung and tmo release a fix, I thought it would be beneficial to create an exhaustive list of all the phone settings where sneaky reporting and syncing is going on. The more I look, the more I find these backdoors in android and starting to get very irritated with the whole android ecosystem. An average user should not have to mess with their phone this extensively to get it to perform adequately. Maybe there is something to what the apple nazis say about an ecosystem where they control high quality. Marshmellow was supposed to come with better battery life (as they promised with Lollipop as well).

Anyway, enough ranting. Here is my list, please feel free to add more and I will update the OP.

Google activity controls - Google now page, settings at the top, then Google account settings, then accounts and privacy, then google activity controls. Turn off location history and other activity controls that you find you don't need.

Diagnostics reporting to Google - Google now page, settings at the top, then Accounts and privacy, turn off "help improve google"

Diagnostics reporting to Samsung - Samsung settings - personal - privacy and safety - Report diagnostic info - Off

Turn off anonymous reporting in Language and input - Settings - language and input - text to speech, google text to speech settings, then settings and turn off anonymous reporting

Turn off other security reports - Settings - lock screen & security - other security - security reports

Turn off access to hardware by different apps - Settings - privacy and safety - app permissions. e.g., Why on earth does google keep need body sensor access?!

Turn off unwanted syncing - Go to settings - accounts and check every account including Samsung, Whatsapp etc. and turn off syncing.

Turn off Contacts searching for nearby places and invoking location - Settings - applications - contacts and turn off "search for nearby places"

Turn off background data usage for unwanted apps - Settings - data usage - go through every app that you don't want background data usage for, and turn off

Turn off unwanted notifications - settings - applications - notifications

Turn off pop-up notifications for applications - settings - notifications - advanced settings - disable pop-up

Turn off push notifications for messages app - settings - applications - messages - turn off push. This does not impact receiving SMS/MMS.

Turn off OK Google detection from everywhere except home screen. Google now page, settings at the top, then voice then "OK google detection"

Other tips I have tried but I am not sure have helped:

Disable google now on tap.

Optimize battery usage for as many apps as you desire.

Disable wifi scanning and nearby device scanning - settings - location - improve accuracy and turn off wifi and bluetooth scanning

Enabled wifi smart network switch

WiFi calling turned off

VOLTE turned off

I cannot live without / do not want to compromise on (so will optimize battery despite the following always on):

Google now with high accuracy location mode

AOD

VOLTE

BT always on

Screen brightness set to 75%

WiFi calling set to on