Garthanos
Arcadian Knight
spread the pain initially to soften them up then focus fire might be a way to see it.the Reason people don’t spread the pain is they want to eliminate the oppositions attack actions. If bloodied = weakened attacks (like 5e swarms for example) and players knew it they might take that path BUT if it’s generally easier to get from 50% to 0 as in the OP s suggestion they will likely take that route
Enemy spreads out after being first bloodied by area effects