So I'm reading that the Galaxy S7 had twice the battery life before it updated to Android 7.0... Makes me wonder - I have to charge twice a day. The LG G4 I was charging 4 times a day under the same use. So it's still a vast improvement.
I am NOT an average user, I'm a heavy user. A normal person goes about 2 hours on the smart phone a day - I go about 6. I also use a lot of apps that are power intensive like doing videos or watching YouTube or rendering videos. So to think that thins thing has half the battery life as on Android 6 makes me stand in awe. I get about 15% or 20% more life if I turn on the power saver mode in "medium". But that also turns off the internet for the apps in the background. This I don't want to have. I already have most of them set to auto sleep, but I want Twitter, Facebook, My package tracker and a couple others to keep hitting the net.
BTW it is a good idea to wipe the system cache after the update to 7.0. You can find out how to do that here. Also keeping the app cache cleaned out is a good idea. Go to the settings - then to device maintenance - then to storage and hit "clean now". There are other cleaning apps out there like Avira Cleaner that will clean off even more junk from storage. If you don't do this from time to time you will literally run out of storage. BTW the more stuff in storage the slower the device runs and the more power it uses.
All this won't double the battery life or anything, but it will speed up operation and give a bit longer life for your day to day usage of it.
One last note, it's normal to drop about 20% every 30 minutes while doing processor intensive tasks like watching movies or playing games. As well the camera sucks battery faster than anything else, so video is fun but yeah it sucks the battery fast forward. Oh and one last note while over in the device management section you might want to hit optimize now and then. It's good to do this once a week.