Yes, agree, that's what I do too but you won't improve 8h of SoT. You just don't.
Like I said, it's down to your usage. You can tweak here a there, and you'll get a couple of hours if you really want to, but you not gonna double your SoT from 6-8h to 15h without really changing the way you use your phone. And who wants to do that?
If you have everything turned on all day and night while you're sleep (why?), play heavy games, social media, couple of messaging apps, GPS and what not, you won't get that kind of SoT.
I get 9h-11h of SoT, I'm happy with it. I don't have many apps installed, only the ones i really need, I use mostly wifi, I have xxx rom with this and that tweek, but i have used stock ROM for the most part and I get good battery life too.
I don't play games at all, I use location only with GPS apps, low brightness, no gestures, etc, but for the most part my SoT comes down to YouTube and other video apps. At least 6h of my SoT is wasted in YouTube videos, tv shows and movies (I do have a habit to listen to TV shows while cooking). All this in 48h. The rest is sms, calls, social media, streaming music with bluetooth in the car, etc.
Im super happy with it. My last phone I would get half of this when the phone was new and 1/4, if that, by the time I bought OP5.
Well, anyway, just flashed this "new kernel" an hour ago. I want to see what the fuss is about. Lol