No one said everybody had to work the same four days. If one custodian works Monday - Thursday and another works Tuesday - Friday, that still covers a full 5 day week. The whole reason for a 4 day work week is that, right now, life is all work all the time. If you work a 9-5 Monday - Friday and you need to go to the doctor, who is only open 9-5 Monday - Friday, the only way to see them is to take time off of work.