Stepping Stone Theory
The Stepping Stone Theory is a supposed fallacy which states that holding collegiate tournaments on high school questions will allow new players to acclimate to collegiate quizbowl on easier material, and thus act as "stepping stones" to participation in more mainstream events.
Back when high school sets like Invitational Series were widely used in collegiate tournaments, it was held that no known examples of the stepping stone theory actually worked. Teams who played high school questions tended to play high school questions forever, and collegiate players who played high school questions tended to drop out of quizbowl when the opportunity to play those questions ended.
Why explicitly collegiate novice questions were not equally able to fill the "stepping stone" role has never adequately been explained, but it may have to do with the fact that NAQT does not collect any money when non-NAQT novice tournaments are held.