Promoted Idol Contestants Go Deeper?

Yes, Virginia, the assumed fact is true.  “Idol” contestants who get pimped in early episodes go much longer than those who do not. Editorials and Articles Archive – – The American Idol Internet Database

Promotional Piece contestants are, on average, 20.2% more likely to advance each and every week than those in the Late/No Exposure group, given comparable performances. Similarly, Audition-only contestants are 14.0% more likely to advance each week than those who did not have their audition aired.

And, seriously, they have the charts to prove it — both bar and line!