[Samsung Galaxy S8+ Guides, News, & Discussion] dhorgas:
All day looking at YouTube = a few videos here and there. I have heard of this usage pattern before and it was always the same.

Surfing Amazon = I do not believe that this is more than 30-45 minutes at most per day, but let's say that it is 2h per day for the sake of argument

Look up NBA stats = a few seconds at most, maybe a few minutes for the whole day

Podcast = likely downloaded, so no streaming, and even at that, screen is off during this time

Talking = screen off

Texting = if you're anything like a typical person, you fire off a few texts here and there, and shut off the screen each time, then rinse and repeat. Again, this probably does not add up to more than 2h of screen time all day

XDA reading = I'm going to assume via the app, dark mode display, minimal battery impact when reading only. Posting takes a greater toll, but you didn't mention anything.

Lastly, you clearly state that you shut services off consciously or don't even turn them on. This is already battery conscious. As far as my definition of a light user goes, I don't have one, but I can define what I consider normal-to-heavy usage, which I am basing on my usage pattern and setup provided below.

At least one work and one personal email account. Push-sync enabled. No less than 20-30 work emails per day, at least 3-5 replies (not one liners, full multi-paragraph emails, sometimes not all completed in one go). Active calendar sync on at least 2 different calendars, approximately 4-5 invites and/or reminders per day, snoozed reminders at least 3 times. Management and triage of personal mailbox on the phone, approximately 20 emails per day. About 2-3 hours of active browser use. Health and fitness tracking all day. 1.5-2.5h of music streaming at high quality (ideally FLAC), out of that at least 1 hour of high-res streaming to car audio via Bluetooth. 1 full length streamed movie per day on average at maximum quality. At least one social network sync. At least two messenger applications with active contacts sync. About 20-30 minutes of SMS per day, plus another 30-60 minutes per day of other messaging apps. Samsung account live-sync. 1-1.5 hours of news reading per day, 50% Flipboard and 50% other apps. Note that I do not play any games. All Google Play apps on auto-update using mobile network. Adaptive audio configured and enabled. All app notifications enabled. No disabled apps or services. Device configured to operate in high-performance mode using full QHD resolution at auto brightness, adaptive display, in a daylight lit environment for 75-80% of the total up-time. No power saving measures at all. No themes that make the display dark. High precision location. NFC enabled for payment support. Full-day Bluetooth connection to Gear S3 Classic with all app notifications enabled. LTE mobile network only, no WiFi (I have unlimited mobile data). Network signal strength is 100% approximately 75% of the time, and between 50% and 75% about 25% of the time).

12 hours of total battery life for me would not get me through the day. My work day alone lasts from 6am to 6pm every day. I will admit that I am not a typical user. I have learned that some time ago. My mobile device is my lifeblood for my day-to-day. I spend so much time in meetings that I live on my device. All my research is done on mobile, etc. I also frequently record my meetings, and these can be multi-hour recordings. I do not play games on the phone.

As a final note, I think we need to establish one thing. We cannot compare Exynos and Snapdragon. They do not have the same level of efficiency. I am not sure if we are, but I just wanted to put that out there. It would be the equivalent of saying that AMD and Intel chips are the same because they are both running x86 instruction set.