Well I have been confirming lately something I had observed in previous campaigns played during Drumbeat; there seems to be IMHO to few shipping along the US East Coast in Dec 1941 onwards. I have been several times there during a campaign and noticed it, and wondered if it was just an impression, a bad choice of the spot to patrol, etc, but a check with the editor seems most revealing: There is not a thick traffic there as you would think. During Drumbeat it was not strange at all for a commander to be engaged in sinking a ship and suddenly another appearing around; in the current status of the campaign in NYGM this won't happen and you need several weeks of patrolling to locate one or two -many times small- ships.
Should be easy to fix, I suppose, by increasing the spawn rate. Probably the origin of the problem rootes to the time when Pentallion, Jace and Nico applied the 20/20 fix to the excessive shipping and US east coast shipping got that treatment too?