Disabling sleep lasts until reboot. Reboot always enables sleep.
KOA2 has faster processor, bigger screen, more lighting LEDs, and smaller battery than Voyage, so battery life won't be great. amazon probably thought deep sleep would fix all this. I don't know of a way to prevent deep sleep while leaving ordiary sleep enabled. No kindle battery will last very long with all sleep completely disabled.
KOA2 can be prone to excessive sync attempts quickly draining the battery. That happened to me and I found the answer in post #2 of the thread
https://www.mobileread.com/forums/sh...d.php?t=323247
(prevents syncing completely)