Who controls Angel Card readings and the Like?

[Cainite]

Do you ask for guidance mainly? Is that the purpose of these types of cards?
Or can they be used for understanding a situation?

Both. there are different spreads. I bet you can even invent your own.

I ask my higherself to manage the reading. and specifically ask the question before choosing the cards.

If I'm affected by a negative emotion at the time I do it, it's usually discouraging.