From my experience the other week it was totally random whether they went to the station or not. I was on one that was meant to and didn't, and another that wasn't meant to (due to the Remembrance parade) and did, with the change being announced at the last minute. Still finding its feet, I think, and it seems that missing the station out if delayed is normal practice.
Overall, though, a 4tph service via the station is probably preferable to a 2tph one going there and a 2tph one not. A bit slower for some primarily leisure journeys, but simpler given the large number of non-regular users.
Well, it sounds reasonable to miss out the station to catch up on delays, and under this timetable any tram can do it unlike the previous complex timetable where some trams reversed at the station and others were scheduled to avoid it