An experience I had on the 23/07/2023 that I can share was a trip I had planned to get down to Waterford from Dublin for a hotel booking.
I was traveling on FIP Coupons (free staff travel) and totally forgot Kilkenny were in the all Ireland final that day.
Heuston was a mad house of people trying to get back on the last service of the day to Waterford via Kilkenny which was completely booked out.
Ispoke to gateline, explained my situation and he said I could get on but I wouldn't get a seat until after Kilkenny to which I was eternally grateful to him because if I missed that, I would probably not have got down to Waterford that night.
Like any other network, taking into consideration events that are currently on takes a bit of homework!
As the gateline lad said, the train emptied in Kilkenny and an almost empty train headed off to Waterford.
Iarnród Éireann is good value and popular to use for people getting to and from major events so it is worth just checking if there is anything on.