43 loading is very inconsistent throughout the day.
Very High: Sengkang (Buangkok MRT) > Serangoon (AM Peak),
Serangoon > Sengkang/Punggol (PM Peak), Paya Lebar - Marine
Parade (AM and PM peak)
High: Serangoon > Punggol (AM Peak), Punggol > Serangoon
(PM Peak)
Medium: Punggol - Sengkang (Peak), Marine Parade - UEC
Low: Punggol - Sengkang (Off-Peak)
I'm not very sure for the Paya Lebar part.
156:
High: Sengkang > Serangoon (AM Peak), Serangoon > Sengkang
(PM Peak)
Low: Serangoon - Sengkang (Off-Peak)