Breaking a journey
 

Is a holder of a day return ticket from Sandymount to Laytown (which, since it goes past Balbriggan, is an Intercity ticket) entitled to break the journey at Pearse (which is on the suburban section) and resume the same day?

It would appear so

Yes, but you can't break DART/Suburban journeys, see 37.1.

Eg Section B 37

In the next two weeks or so I plan to get the 1110 Galway train to Kildare, meet a friend there briefly and then continue to Kilkenny on the 1130 Waterford train. Can I do this with a return ticket to Kilkenny? If the answer is yes but the checker at Heuston says I can't do that what can I do then?

I think you have to take the whole journey in one go and the one train. But I did it once on the 09:00 Cork and got off that Kildare this was last year. I wanted to see what the new Intercity MKIV's were like. I got off at Kildare and waited for the Waterford train. The ticket inspector allowed me to do this maybe things have changed........

The rules clearly permit any passenger traveling to break their journey unless otherwise indicated

The exceptions are all tickets between stations within the Dublin short hop zone, Maynooth/Balbriggan/Kilcoole and Hazelhatch, Also Cobh Cork

that exception to the rule should not apply if there is bad timetabling. For example Hazlehatch-Dublin at times has woeful service and if there is a chance for passengers to get to their destination earlier by breaking their journey they should be able to.

Breaking of journey is more to do with you leaving the station doing something coming back and continuing

Breaking your journey as in changing trains en route as required to complete the journey in the shortest time is always permitted, how else would you get from say Seapoint to Maynooth?

Journey made without problems and on time in both directions. Only issue was the ticket machines at Heuston. First one I tried refused to work with any cards and the second rejected two of the three (known to be fully functioning) cards that I had with me.

I was very impressed with how clean and tidy Kilkenny station was

AIB issued cards seem to be troublesome, particulary Mastercard ones

Lasercards best avoided, unless you know yours works

Yes my fiancée was never able to use her AIB Laser card in either IÉ or Veolia TVMs. She hasn't had any problems since moving to Halifax though.

I would have thought living in Halifax would present a problem with using the Luas and IE.

:D :D