An inconspicuous planning parameter with a huge impact: the weekly deployment factor

by Dr. Jörg Herbers

Much has been written about workforce management and even more has been discussed. Common topics are working time productivity, staff costs, and service levels.

From the employee perspective, it mainly concerns planning of leisure time, physical strain due to varying working times and the limitation of social needs. In particular tiredness and insomnia are constant companions for many shift workers, often well into retirement.

There are a myriad of opinions and approaches as to how the challenges of decent workforce management can best be mastered. More and more experts are becoming involved. Concepts such as working time flexibilization, annual working time accounts and employee participation are on everyone's lips.

Everything is easy with a 5-day week

Which makes it all the more surprising that there is one shift planning parameter that is almost always absent, despite the fact that it is a planning variable that is obvious, as well as significant: the weekly deployment factor (WDF). For the employee, it has a direct impact on the annual number of working days - and thereby inversely on the number of days off per year.

The weekly deployment factor defines the average number of working days that an employee performs per week.

Beyond shift work, the WDF for full-time employees is usually 5 days per week, distributed between Monday and Friday. In this case, the average daily target working time is easy to calculate. With a contractual weekly working time of 40 hours, a WDF of 5 gives an average target working time of 8 hours per day.

Sickness and vacation correspond to 8 hours of actual working time per day, irrespective of which day it occurs.

In shift work, it becomes more complicated

For companies with continuous shift operations, the distribution of the weekly working time over 7 potential working days isn't a fix dimension. On the contrary, it is the challenging and diverse task of workforce management. It requires optimally deploying the employees' working time while considering various interests and objectives.

The options are usually regulated by a company agreement. In principle, all elements of the working time model can be defined there. Common agreements relate to:

  • shift length and shift start
  • minimum / maximum lengths of 'on' and 'off' blocks
  • weekends off
  • night shifts, especially upper limit in sequence
  • minimum rest time, especially following night shifts

Misconceived fairness

If regulated at all, the weekly deployment factor is usually set to an upper limit of 5, either explicitly or implicitly. This results from trying to equalize the number of working days for shift workers and non-shift workers. Usually, the aim is a fair equal treatment.

If one follows the thought that it is the ultimate purpose to reduce the physical and mental strain of shift workers compared to non-shift workers, it is questionable whether a WDF of 5 is sufficient. For example, the recommendation that, due to the increased strain of night shifts, 3 days off should ideally follow a night shift block, is generally only possible with a lower WDF.

It is equally questionable to assume that the needs of all workers are the same and that fairness and employee motivation can be achieved by giving all workers almost identical shift patterns, based on a uniform working time model. On the contrary, the strain on the individual can only be improved if the particular needs of the employees are considered in the planning.

Weekly Deployment Factor - crucial for days off and vacations

This also applies to the WDF. Mathematically, the WDF is directly dependent on the average shift length, for a given weekly working time.

For clarification: a contractual weekly working time of 40 hours with an average shift length of 8 hours results in a WDF of 5. However, if the average shift length is 10 hours, the target working time would be achieved by working an average of 4 days per week.

The WDF has a direct impact on the number of days off. With a WDF of 5, there is an average of 2 days off per week - or 104 days off in 52 weeks.

By increasing the average shift length to 10 hours a day, the days off per week increases to 3. That makes 156 days off in 52 weeks.

Thus, an employee who works an average of 10 hours per day has 42 extra days off compared to an employee who works 8 hours per day - with the same total working time.

Those who work a 7-3-7-4 shift pattern have a WDF of 4.67, resulting in 121 days off in 52 weeks. That is 17 more days off than a 5-2 pattern generates.

Also, the annual vacation entitlement is linked to the WDF. This is often not immediately clear to those involved. Although it is evident when one is aware that the annual vacation entitlement is usually in days, but the actual working time is measured in hours.

Example: with an annual vacation entitlement of 30 days, a WDF of 5 equals a total of 30 * 8 = 240 hours. The same value is provided to an employee with a WDF of 4 and an annual vacation entitlement of 24 (24 days * 10 hours per day = 240 hours).

The dependency between the annual vacation entitlement, expressed in days, and the WDF is therefore entirely correct. However, this correlation is often misunderstood.

Offering choices in an optimal way

Although the WDF directly affects the number of days off, it cannot be freely customized, nor is there an optimal value.

On the one hand, the increased number of days off is countered by an increased strain due to longer shifts. Which side of the coin matters the most is a question of personal preference and depends on numerous factors, often on age. Younger workers may tend to prefer more days off, whereby older workers may place more value on shorter shifts. This is also strongly dependent on factors such as travel time and costs. Those who live close to their workplace find an increased number of working days less of a strain than those who have a long and/or expensive journey.

On the other hand, from the employer point of view, the economic goals also play a role. Ultimately, it is about meeting the working time requirements as efficiently as possible. The amount and fluctuation of the working time requirements directly determine which shift lengths are the most productive.

Typically, there is not just the one most efficient shift length. More often, in times of increasing flexibilization, companies are forced to use shifts of quite different lengths. In addition to the employment of part-time workers, the use of various working time models is an obvious solution. Instead of offering all employees just one single working time model due to an incorrect understanding of equality, a differentiation makes much more sense. Why not offer employees a choice to select the model and the WDF that suits them best? In the end, both sides can benefit from this.

Which role does the weekly deployment factor play in your company?

This article was originally written and published in German and therefore links to sources in the German language. The original article can be read here.

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About the author

  • Dr.

    Jörg Herbers is Senior Vice President Workforce Management at Inform GmbH. He specializes in all topics related to staff planning and optimization.

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