If that was the case, it would be the other way around. War mode on increases other things by 10%, so blizzard sees having war mode on as more challenging. It’s just rng when it comes to upgrades.
What I can say, is it’s kinda like getting personal loot in raids. Say you need a piece off the last boss, but you just got a personal loot piece from 2nd last. You might want to considering going and doing another raid that PL works in, and doing that till you think your about to have a drop, then stop, go back and kill last boss or whatever boss u needed in first raid, and hope now your PL will proc for boss.
Treat quests the same way. If you feel a rare or epic proc coming, go turn in that quest you want to be upgraded. A lot of rng still but this will make it slightly easier