The single most difficult element of a schedule is the employee.
Why? An employee is a human being with his own life, his own goals, and his own projects. That employee has plans for their life and they are changing.
For an employee, that schedule you create is their life. That person will have to plan all their personal activities and family obligations around it and that person will try to get the best schedule possible for their own benefit. As people grow older, the benefits will change over the years. What was a good thing for that employee last year (lots of overtime) may not be good this year because that person just entered parenthood. This means that just like the workload changes, your employee preferences will also evolve.
Employees want to be treated fairly. Folks who get hired into a job that has varying schedules know what to expect, but they also want to make sure the bad schedules (the weekend night shift for example) doesn’t always fall on them.
The schedule is known to be one of the key elements that cause turnover. Anyone in Human Resources would tell you what the cost of turnover is and the importance it has. I won’t make that point here, but I will state that for employees who are scheduled, they will change jobs in a heartbeat for a better schedule simply because it means a better life.
You need to establish expectations for the workforce. The clearer they are, the easier your life will be. Don’t put reality on a positive spin or a negative spin: tell the story as clearly as you can to your employees. Otherwise, any gray area will be made up by people. Nature does not like holes and fills them up quickly. Therefore, any hole you leave in your story will be left for people to fill with whatever is good for them (an optimistic person will fill it with happy thoughts and the pessimistic will see a plot to squeeze all the employees and abuse their good will to the bone).
Any HR specialist has a whole bunch of directives to give planners and management and what to say and what not to say to employees. In the end, it’s all about humans and future entries will examine more aspects around the employees and the points to look at when scheduling is concerned.