The track cuts can be affected by temperature and weather. If it is too cold, they will delay the process. The Merrick-Bellmore / Massapequa Park track cuts were done over a Friday evening and Saturday timeline. While there were no revenue trains in a split configuration (like Wantagh / Seaford), during the actual cutover there were some spit configuration operations. As for Amityville / Copiague /Lindenhurst (ACL) opening on Tuesday 7 AUG 73, I am not sure how that transpired (you would need to read a village newspaper from that time for more insight or check with the Town of Babylon historian to help you research the subject). Since a Tuesday seems like an odd day to execute the changeover it may have operated a few days in a split configuration to minimally disrupt service on the Babylon Branch or work crews probably made the cut over after the morning rush hour. Wantagh Seaford opened on a Wednesday (22 OCT 68), a little over two years after the temporary tracks went into service (Wednesday 24 AUG 66). It seems to me they would have run a few test trains (first diesel then electric) across the ACL span before opening the segment.