I worked with a guy, a Baptist of the very legalistic type, who set his thermostat back to 55 all the time.
His wife and two little kids were at home in the freezing cold all day, and the kids ended up getting sick and he still wouldn’t turn the heat up, while he was in his nice, warm office all day for work.
My family did drop the thermostat a few degrees, which was really no hardship. My parents kept the house way too warm.
68 degrees is the lowest I’ll keep my thermostat during the winter. I won’t go lower than that.