In 1931, G\"odel presented in K\"onigsberg his famous Incompleteness Theorem,
stating that some true mathematical statements are unprovable. Yet, this result
gives us no idea about those independent (that is, true and unprovable)
statements, about their frequency, the reason they are unprovable, and so on.
Calude and J\"urgensen proved in 2005 Chaitin's "heuristic principle" for an
appropriate measure: the theorems of a finitely-specified theory cannot be
significantly more complex than the theory itself. In this work, we investigate
the existence of other measures, different from the original one, which satisfy
this "heuristic principle". At this end, we introduce the definition of
acceptable complexity measure of theorems.