For international through Germany we used to get 100% back after four hour delays but they stopped doing that ... For obvious reasons. I traveled for free multiple times in the (long) past. Also fun of you wanted to get more back: if you had a first class ticket and reserved seat and had to switch trains and re-reserved you would get a free ticket with a stamp price for about 5 euro. Which you could ask back. So you got at least a coffee for free.