No one reads the fineprint.Thanks. I get 25-30 hours usage from a Paperwhite and I'd be happy enough with half of that.
Some of the reviews on Amazon are laughable, even for the Paperwhite. People read 'weeks' of battery life and think they can use it for hours per day and achieve that goal. Then they give it one star because they have to charge it once a week while they're asleep as if that was a real problem.
Iirc, the disclaimer was:
6 weeks, 30 minutes/day, brightness 10, wifi off
So around 21 hours.
Mind, there was an issue with some PW4 firmware versions being overly aggressive at pinging Amazon for automatic updates. My PW4 was draining at 1% per hour on standby with no indexing going on if I don't put the PW4 on airplane mode. Thankfully, someone found a fix.
https://www.mobileread.com/forums/showpost.php?p=3804435&postcount=326
Note, since e-ink consumes power with page turns, the more frequent the page turns, the faster you run through the battery. Using larger fonts or reading content like manga (Japanese comics) use up battery more quickly. When reading manga, I actually just get the same battery life on both iPad and Paperwhite.