While loops cost money leaving extra loops in isn't just about the timetable. They have a serious effect on service reliability.
On the Sligo line over the last two years we have had two or three extended periods of disruption due to flooding near Longford. What should be a 15 minute delay due to a bus transfer ends up being pushed out to 45 minutes or an hour because there is nowhere between Killucan and Maynooth to cross trains outside of the timetable. Enfield only has one platform and no bridge so one of the crossing trains has to be timetabled not to stop there.
With all the rain over the last 10 days or so things are not looking good.