>> I always find that feature annoying...I've left my reserved seat for the restroom or restaurant car and someone took my seat once! I had to go to the trouble of showing tickets to get them to move.
Yes, that is a bit of a risk! I have developed a few tricks over the years of travelling on trains by myself in Europe! I time my visits to the loo and restaurant to avoid times when the train will be stopped at a station, and within the first 10 minutes or so after a stop. So that means I will be in my seat when people are boarding, or walking through the train looking for a seat. I also leave something of little value on my seat whenever I leave it, such as a bottle of drink, packet of tissues, snack bag etc - although that is just as much to help me recognise my seat again when I come back, as to discourage anyone else from sitting there!
There's another good reason for not being in the loo when a train pulls into a station, as I discovered earlier this year, when I was travelling with my son in Sweden. I came out of the loo, which was in the next carriage, just as the train stopped at a station. It turned out that the carriage where I had used the loo was uncoupled, and left behind at that station. Had I still been in the loo, I would have been left behind too, while my son and luggage proceeded on their way in the other half of the train!
I once experienced a little incident with reservations in the Bernina Express. An American couple boarded, stopped next to my seat, and asked me to move because I was sitting in their seat! I checked my reservation, and I had the correct seat. Theirs also had the same seat numbers, so at first I thought there must have been some sort of mix-up with the allocation of seats - but it turned out they were in the wrong carriage!
>> Seemed odd to me..Is this just a Swiss thing? I'm sure in other countries the reserved sign stays on the while trip.
On Deutsche Bahn it works the same way, but they only wait 15 minutes before releasing the seat! I'm not sure about Austria. The only time I ever tried to reserve a seat there (because I was travelling with luggage from Vienna to Innsbruck or Zürich), the ticket office staff in Vienna talked me out of it, saying it was unnecessary!
Something about reservations I used to wonder about was how you can make a reservation right up until just before the train leaves, without having to turf someone out of the seat, who might already have sat there before it was reserved. Then I discovered they keep some seats aside for last-minute reservations. These seats have "ggf freigeben" on the electronic display above the seat that shows reservation details. This is short for "Gegebenenfalls freigeben" (vacate if need be), which means that the seat will need to be surrendered if anyone turns up with a reservation for it.