They have to. They are bound by law. If they don't terrible days are ahead and it won't be good for Google, Samsung or us.

I have an M20 an I have been using it for the past 4+ years. My battery gives a backup for 23 - 24 hrs.I use CCLEANER to keep all the apps sleeping or force stop them. I also use the phone in ultra data-saving and power-saver mode.