Weekly Day Off for Employees
Every employee is entitled to a weekly day off legally. There is no need to give the day off to everyone on the same day. This is not possible given the nature of your duty, which follows a 24x7x365 schedule. It is possible to provide them with a paid day off for every 6 days of work or duty (not as leave, as you mentioned) on a rotational basis. This information must be posted on the Notice Board and submitted according to the applicable Labour Act.
Rotational Basis and Practical Adjustments
The exchange of these days off among employees on a rotational basis is feasible due to practical difficulties and emergencies. This temporary adjustment between them does not need to be communicated constantly. Proper attendance tracking is sufficient. However, I have observed that some security agencies have a system where employees work continuously for 2/3/4 shifts with breaks for natural needs and meals, followed by a day off. I am concerned about how this can function without jeopardizing the health of the employees involved.