One of the weakness of the mirrorless cameras is what has become the “poor battery life”. In the “good old days of 2010/2012” if the battery life of a DSLR was 300 exposures, it was rated as OK to Good. In 2017, a battery life of 300 exposures is rated as poor. So all the mirrorless Are trying every trick in the book to squeeze more life out of the battery.
The AUTO POWER SAVE is just another of these setting to try to extend the life of the battery.
The AUTO POWER SAVE only applies to the LCD and the EVF of the X-PRO2 and of course the X-T20 and the X-T2.
The Auto Power Save does nothing when using the OVF with the X-PRO2.
If the HIGH PERFORMANCE or STANDARD is selected with POWER MANAGEMENT settings then the LCD and EVF will switch to a standard-quality display when the camera sits idle for the set period.
As soon as you do something, the EVF and the LCD will return to the high quality display
I do not use the AUTO POWER SAVE feature, I take my photos and turn the camera off and turn back on when I need/want to take a photograph.
a longer battery life is more important to me, and the X-PRO2 is fast enough on start-up for me.