50 Game 3
Comments

In what type of games are "rules of two" most common? I feel like I often miss them because I don't know when I should be looking out for them

There isn't a necessary relationship between the organizational template we use for a game and the presence (or absence) of a rule-of-two possibility.
That said, it is probably more likely that you'd get the chance in a grouping game (where you have fewer overall options of where to put things) than in an ordering game (where it's likely that each element has up to 7 different spots it could go in).
What you can do is, as you symbolize each rule, you can ask yourself "Does this rule limit some item/s to only two possible places? Does it limit some space to holding only two possible items?"
If so, then you can show that duality in your diagram.
Make sense?