When I went to Europe backpacking the rude shocker was waking up in the middle of the night because that seat was not reserved. I thought that train only had unreserved seats. From next day I started adding reservation with that extra cost every time I had to reserve seats or berths and then seeing a lot of Europe essentially had just buses as public transports and not trains (esp. when I moved towards Eastern Europe -- also in Sarajevo I believe the pass didn't work, I had bought that in AMS).

Maybe next time I will manage it better. Is there a pass that doesn't require you to pay extra every time you want to reserve a seat/berth on the train if you already have a pass?