Imbalance on the (1)

This weekend, there is a G.O. that southbound trains run express from 34th Street to Chambers. The trains will arrive South Ferry sooner than their regular schedule. There is no northbound G.O. for trains to run express. Are trains held to leave on their regular turn around schedule? If yes, it seems there will be congestion.

To alleviate congestion in the loop, is there a special timetable or are some trains turned at Chambers? (The G.O. mentions nothing about turning trains at Chambers.)