It is sort of wrong, here's how I envision this would work:
Depart from 242nd Street:
Every 6 minutes Rush Hours
Every 3 minutes Rush Hours
At Dyckman:
If needed when there's a directly behind a , trains already between Dyckman and 168th go directly express to 168th, while the runs local to those bypassed stops.
At Rector:
If service is backed up, trains go out of service at Rector then proceed through the loop back up to Rector, trains run to New South Ferry.