deltronMost Zojirushi rice cookers have a feature for fast cooking that can be activated by either pushing the start button twice or selecting a fast mode. In that mode, they take about half the time. I've used three different rice cookers (two by Zojirushi) that were able to cook the rice in about half an hour.
deltronIt's always starts at about 55 minutes because it lets the rice soak before boiling it, regardless of how much rice is in the pot. I find in practice that 1 "go" cup (the Japanese measure of rice, about 80% the size of a US cup) takes about 50 minutes and 3 "cups" take about 1 hour. The change in time is probable just the difference in how long it takes to boil that much water.