When I buy a ticket, it's only for one ride? I'm from Pilsen. When I buy a ticket from us, I pinch it when I get on the bus and I can't go again. Is it the same in the subway?
In PID (Prague Integrated Transport) there are one-time tickets (so they work the same as you state), but also time tickets - 24 hours, 72 hours. And the same tickets - of course, work throughout the system - ie for the subway, trams, buses, trains ... See - http://www.ropid.cz/tarif/cenik-jednotlivych-jizdenek-plnocennych__s189x1109.html