[Nexus 5X General] bblzd:
Depends which background services. With just default Google ones there shouldn't be serious battery life issues, but once people load up their own apps and services everything is up in the air at that point. It stops being Nexus 5x battery life and starts being personal battery life which is determined by the general headings I like to simplify as: Usage, Settings and Signal.

Wake locks and weak signal are two common issue with battery life and happen with any device of any battery size. The other big one is apps but we have no easy way to determine who has which apps installed or which ones are not behaving properly.

All your results have been short examples with mostly voice calls. Voice calls don't use the screen so your screen time will appear to be low. Text messaging also doesn't use much screen time as it's mainly just radio and keyboard drain with just a few minutes of screen.

If you do something during your example that requires the screen then you will get more screen time. This is basic stuff TBH.

He also mentioned he was using 0% brightness (less actually he had it on -30% using Lux but that does drain more battery versus simply using 0% as it draws an overlay over the screen). Custom kernels can make a difference but that comes at the cost of reduced performance as nothing is free.

Phones need deep sleep to last more than a few hours on battery, so for each app someone might have installed that runs in the background that will equate to less deep sleep time and higher drain.

I disagree that they just need to add bigger batteries though. Larger pool is always nice but you can find the exact same complaints and screenshots you see in this thread for any device. Go to any device forum with a 3000mAh battery or bigger and you will see the exact same things you see here, typical battery issues regarding wakelocks and weak signal.

I'll say it before and I'll say it again. 2000mAh or 3000mAh barely even makes a difference if the phone is being kept awake and can't deep sleep. Either one would drain in just a few hours. It only takes one wakelock keeping the device from sleeping and to ruin everything. Everyone has different apps, different settings, different signal types and strengths, etc. and they all have potential to effect battery life significantly.

I think we need smarter batteries not bigger ones. That is why the iPhone 6s can get good results with just 1700mAh at its disposal.

All we can say for sure is that on its own the battery life has been shown to be good. From there some people drain it to the ground in a few hours and some people can go multiple days without issues, as will always be the case. Its not surprising to me at all that some are getting good and some are getting bad battery life, that's how it's expected to work and you can see the same thing with every device.

One of the many reason why results can vary wildly is because the Snapdragon 808 SoC has 4 very efficient low powered cores (4x A53) and 2 extremely power hungry cores (2x A57). Depending on how each person uses their device and how many apps/services are running in the background there will be large variations in SoC power consumption based on which cores are being used. Web browsing would be mostly low powered cores sitting idle and would equate to long battery time and screen time.