Some ppl blind never see the punngol and tampines mah. :D
Thing is, it's okay for 3 towards punggol to be outside interchange
because it saves time and in the bigger picture, fuel.
I've taken 3 all my life and always ppl go straight to inter to
take the one to tampines, why? Because convienient, and got
shelter, so cannot kick 3 out.
The reason why Service 3 calls Pasir Ris Int because it was
meant to serve ex-357's route. In order not to cause inconvienience
ex-357's regular, service 3 will call inside Pasir Int towards
Tampines.
Feeders serves a purpose, by making a trunk service to take over
a feeder service. The operating hours of the service must be
extended to end after the last train depart that station.