About ticket checking on LIRR?

It's happened to me a few times but I use the LIRR a lot. She can use the ticket between the same points or use it between any other points that the LIRR goes to. If the total amount comes to more than the ticket is worth, she'll just have to pay the balance to the LIRR ticket taker on board, but if it's less than the face value of the ticket, she will not get a refund of the excess.