Wow. I've never had that bad of a problem with any of my phones before, but it does seem though starting with the S6 from my experiences the batteries on these things are a bit wonky. My s6 didn't get good battery life and that thing seemed to drain fast, then again we all know about the terrible battery life of the S6, my Note 5 had okay battery life but even that was so so and would drain fast, and the Note 7 my battery life is meh. I'm not seeing the super long life like all the reviews are claiming. It seems about the same as the S7. Bigger battery doesn't mean everything. These Note 7s have bigger screens, Always on, and Spen so the bigger battery is compensating for larger screens and such.
Since these phones don't have replaceable batteries I wish Samsung would put more research and development into finding ways to give us longer battery life.