That government literature didn't give any hard numbers, just percentages.
Obviously, it costs money to operate the HVAC system.
Forced air heat seems to be able to recover an ambient temperature relatively quickly. My home is 72 degrees for about 8 hours a day in the heating season.
Cooling doesn't seem to work that way, and I have found about a 3 degree swing to be about it, otherwise, the equipment is on for a much longer time to recover the temp.
My home is shaded and on a slab, so if it is cooled to 77 at night, it takes a while for the AC to kick on at 80 during the day.
I bet that if everyone raised their t-stat by 1 degree in summer and lowered it the same in winter, the energy savings would be much more than a setback stat.