Officers will have the informations put on weekdays (except for statutory holidays), I don't think they work weekends.
However, one time I checked e-CAS late on a Friday evening (May 15) and no other information other than that they had started processing my application on May 8 was available. When I checked again on Saturday, it stated that the application had been approved on May 14. Perhaps those would be automatic updates, though (the system already had the info, and then it updated on its own to display the newest info), or perhaps they updated later at night... For clarification: the application had been a request for urgent renewal of PR Card.