Magi generally work magical effects through some sort of conscious effort, they've got the whole Imago and casting tools and what not.
But are there any ways you can think of where a person could be the focus of magical effects, and maybe even unconsciously responsible for the effects, but not consciously or intentionally producing the magic?
I remember from reading there were Arabians who didn't necessarily think they were doing anything magical, they just expected the universe to work in a bizarre way, and their magic made the universe conform to their insanity. Or stories of magi whose world view was a little skewed and their HGA obliged in making it how they expected it.
The sort of unconscious magic I'm thinking of would be more a personal thing rather than a culturally accepted set of practices.
I think that certain people have an subconscious understanding of magic. That's why even when not trained some people can sometimes display great feats of magic (although it might have taken them less time had they trained). I wouldn't go as far as to say it's intuitive, just subconscious.
Building on this assumption I'd say that Theurgists can cast magic subconsciously, but thought I would see what others thought.