With sadness, I think the broad answer is likely never. For a given piece of hardware Linux support generally improves over time, but new hardware continually

With sadness, I think the broad answer is likely never. For a given piece of hardware Linux support generally improves over time, but new hardware continually comes out so support is continually behind. You need the OS vendor, the kernel authors, and the hardware vendor to all be in sync for this kind of thing to work out well. With that out of the way, it is possible to diagnose and fix the problem yourself. sudo apt-get install powertop, read some docs, experiment a bit. (Right here is where someone injects "buy a Mac".) And if you go the "safe" route and pick a laptop popular with Linux users, like a Thinkpad, you'll likely have better luck. My laptop (an X201) gets around 6 hours and I haven't changed anything.