If you buy a normal, point to point, ticket you can indeed interrupt your journey and continue on a later train. You can also take earlier and later trains. Basically such a ticket is good for one trip on the route you bought it for, on the day it is valid. You are not limited to the trains you selected during booking.
With Supersaver ticket you are limited to the trains you selected.
However, for your trip probably a Saver Day Pass will be the best option. This is good for unlimited travel on all public transport in Switzerland, so offers you full flexibility.