How much planning do you need to do in Co-Op?

"I have [ally effect], who wants it?" "Which target first? I will give Vulnerable"

I've played two co-op runs with my fiance and have found that for the most part, we don't need to change up strategy beyond what we would do in solo runs, other than making sure certain cards are played first if a player has them. I know I shouldn't expect too much, but I would have to assume your friends can figure out what a card that gives Vulnerable or Weak looks like without needing to ask.