In sequence or not?

A most interesting question was posed to me on the Aleister Crowley Society Web Site on the forums. The essence of the question was whether the cards should be placed in sequence before a reading is done. My own feeling is that the universe that the tarot mirrors does as it pleases and that the cards need not be re-ordered. But I am definitely not the world's most experienced reader. Any opinions on this? Has anyone got some verified experimental results?