I've seen people say 'I'd take an inch thick phone if it gave me a week of battery'.
But would you? For one thing, imagine how heavy that would be. Having to take a phone which weighs about a kilo and won't fit comfortably in any pockets, weighing down your clothes and sticking out. And how hard is it to just plug your phone in when you go to sleep, or with the fast charging capabilities we have, when you have lunch, or other times when you might not be using a phone, providing you don't forget? I can understand a bit of heft to get you through a full day on any occasion, or to get you through a few hours without charging it, but an inch thick phone for a week? Sorry, I'm not getting it.
I think advancements in batteries won't lie in getting you through long periods of time, but in better fast charging capabilities. If my phone could charge in 10 minutes, which at the rate we're going at today, could happen within the next few years, then I would take 2 hours SOT. Not joking. Fast charging today is a bit overblown. Sure, it has improved, but waiting 90 minutes without using your phone while waiting for it to charge completely is a bit unrealistic for ideal use cases. I find that currently, the first 50% charges about as quickly as the last 10%. If they can get a consistent rate of charging throughout the whole process, that would be a huge step forward.