NWI-EDI
Nick,
Interesting spot but it may be that given some of the NWI-EDI block-times have increased it switches to a Saab 340 instead of Dornier. That would allow the EDI gap to service a KOI / LSI / SYY rotation before returning to NWI, also allowing EDI tail swap.
Not sure there is 4 x rotations NWI-EDI, just some variable schedules to align more to demand it would appear. Sensible scheduling.