The iron curtain has been placed on the PER flights, but not every flight apparently. Overheard a rather irate conversation the other day from a 420 flight that was not installed with the curtains. I'm not sure if they got them in the end, but they aren't nogo items at the end of the day.
Be warned, the crack management team of CSI's (Crew Sickness/Sleeping Investigators) will still drop down on ANY crew who admit to sleeping outside a curtain like a ten ton heavy thing.
Be sure to tick the appropriate boxes regarding crew morale in the survey.