Both the N and the Q run local overnights. The Q switches to the local track N/B before prince st and switches back south of 57/7. They don't "trip over each other". And yes, during overnights the Q makes all local stops from Canal to 57/7.
Now as to relays from a few posts back, yes, the F relays at 179. Always does. It arrives on the east bound platform and departs from the westbound platform. relays includes:
Bronx: 205 , Parkcester
Manhattan: 168th , Brooklyn Bridge , Bowling Green , Broad St , Chambers (J and M when needed)
(not sure about overnight 3 train)
Queens: 71/Forest Hills , 179 (F, E), Broad Channel (Rockaway Blvd-Summer weekends only)Rock Pk Shuttle
Brooklyn: Church Ave , Euclid (C and Lefferts Shuttle), Utica , Kings Hwy (F, only during the rehab)
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