No matter all the constraints you put in, an event will happen that will force the planner to break the rules. The most common is to ask employees to stay for another shift (double shift) which breaks the minimum rest rules. Areas like transportation do not allow this practice by law which would expose them to severe fines, but manufacturing and healthcare industries often ask their employees to work double shifts.
Another common broken rule is the maximum consecutive days of work. Once the schedule is published and the actual planned day is about to be worked, the planner will ask for overtime and employees may end up working more days in a row because of an additional overtime shift on a day that was planned to be a day off.
While you can be very detailed about your constraints, you also need to identify which ones can and cannot be broken. Otherwise, the planners will decide themselves which ones to break causing legal issues later down the road.
Some industries identify a set of constraints that apply when the schedule is built and published and another set of constraints for the maintenance and the management of the schedule. This way, the planners do their best to create a schedule that covers the workload knowing full well that things will change anyways. Therefore, some flexibility is given to planners so that they can make modifications to the schedule when reacting to changing circumstances.
The important thing to remember is that some constraints should be put in place as guidelines and others should be enforced as law. Once all of them are listed and documented, it is up to the business to determine the value of each constraint and decide to apply it or not. The more constraints planners have, the more difficult schedules become.