That is not my experience at all. Running Debian, my 7 years old cheapo 4th gen Intel laptop on its original battery still gets a good 6 hours of battery life.

That is not my experience at all. Running Debian, my 7 years old cheapo 4th gen Intel laptop on its original battery still gets a good 6 hours of battery life. If a laptop gets much worse battery life on Linux that's a good indication that its hardware is not supported. It may be for example a dGPU that is not initialized properly and sips power as a result.