For the purposes of this discussion, if you get caught using, you get caught using. A guy may use once and get caught, and another may use all the time, but does that make him different in the eyes of the rules when receiving their respective punishment? Does the guy who only used once not get branded as a past steroid user? If you use and get caught, you got caught cheating regardless of your usage patterns.
And for the record, Petitte's statement that he "only used to recover from a surgery" could be ******** for all intents and purposes.