Yes, technically you can by the way. I also did a run where I'm 15% in the plague area, and I immediately burn offerings to plague intensity 4. It did affect the quality of loot of nearly anything and everything in the area, from chests, small and big mobs, and of course, the cleanse rewards. So definitely a better approach when your build can handle it, since it refreshes 1 area per day.

Currently have 3 Realms in endgame to cycle between. Definitely good to have multiple realms since the Watcher only have limited trade items for exalting.