Its faaaaaaaaaaaaar easier as you thought-in the Swiss all trains run so often-like Vrail around MEL or State(strike?)rail around Syd that they do not bother with RES. Are those trains always so full that one is unable to find an empty seat? RES is for big groups and the like (boyscouts, schoolclasses)-they get a own section in a car
Pretty nice ride along lake Geneva for first half_ take a seat on the right hand side when dep. from Gnv.
BTW-some 95% of all trains running anywhere here in EUR are like that-but its more that all newbees tend to want to use those trains that are hard to get. Partly explainable-the long-distance expresses going over borders and hi-speed, but partly also due to notsosmart planning.
On average seat-occupancy in most countries is about 45-55%-that means that on average about half of all seats in running trains are taken at any moment. But this can vary from 0 to 111 depending on line, day of week, season etc. (yes, it can be higher-3 kids on 2 seats)
Making reservations is not needed in Switzerland. Almost nobody does it and IMO it's a waste of money.
Thanks for your answer @mcadv :)
I am sorry that I am still a bit confused. Does that mean there's no way that I can book seat reservation in advance? Do we just hop on at the train station with our Eurail passes? Thank you 
Making reservations is not needed in Switzerland. Almost nobody does it and IMO it's a wate of money.
Ah I see, thank you a lot
