I work flexi time (40.1 hours a week). I winter I'm a bit lazy but in summer I often do 12-14 hour days and then can take Friday off
I love the flexi time because on days like today (blizzard) I can start at 09:00 if I like and in summer when it gets hot I can start at 05:00 and go home at 13:00 before the worst heat comes.
Btw, have you noticed that 24 weekend hours are much shorter than 24 working day hours? Time is more relative than Einstein thougt.