Could you include an option to increase the time of the screen on in the same gallery?
Example, you tap on the circule circulated to bring up the time options, 2,3,5 or 10 mins.
this is efficient when reviewing documents or photos without having to leave the gallery but, without affecting the time that you chose in Display inside the settings.
Set up a Bixby routine. I set up routines to change the screen time out when I use certain applications and it automatically resets to default when you exit. Works great.