I guess it's a bit on how various technologies are optimized within the system. My Steam Deck can hold quite some battery juice for a while, but i will never be more amazed than my original Nintendo DS, that still has lots of battery capacity even after years and years of neglect.

For my current laptops i have been ignoring the battery completely. I rather have max performance, so every energy saving thing gets disabled. Most of the time it's connected to power anyway.