The striking evolutionary conservation of ratchetting points
suggests that recursive splicing provides specific advantages for large
introns, ... One possibility is that recursive splicing
prevents the generation of long RNA transcripts that could form
structures that interfere with correct processing into mRNA. Another is
that recursive splicing might help stimulate transcription through long
introns by promoting interactions between the splicing and
transcription machineries. We also know already that recursive splicing
is used to control the removal of certain exons from mRNAs, generating
structural and functional variation among the gene products.

Javier Lopez