Afaict, a lot of them exploit the asymmetry of initiative.

The audience member doesn't know how many times a magician is "supposed" to ask or do X.

The magician, on the other hand, has free reign to choose when and how often to do so.

Leveraging this + secret information (e.g. the current ordering of cards in a deck due to a perfect shuffle) = magic

But as others say, the trick is making the above look convincingly effortless and spur of the moment.