Why is Scheduling People Hard?
Most people do not realise just how complicated staff planning and employee scheduling can be. Surely it's just a case of allocating some work to people until you have covered all the jobs? However, even a very simple example demonstrates why the planner's task is in fact extremely challenging:
Imagine that you have 3 people (A, B & C) and 3 jobs (1, 2 & 3). Each person can do one job, but some people are better at certain types of jobs than others so we want to work out the best allocation of work.
What are all the possible ways of assigning these three jobs? One possibility is: Person A does Job 1; Person B does Job 2; Person C does Job 3.
Or, A could do Job 2 and B could do Job 1. Or, C could do Job 1 and B could do Job 3, etc. In fact there are 6 options for the allocation of work to people, as shown to the right.
So, in theory we have to consider all 6 possible allocations and choose the one which best matches people's skills to the type of work. Of course this specific case is very easy and takes no time to solve.
However, imagine there are 4 people and 4 jobs instead. If you work out the number of combinations you will find that there are actually 24 different ways of allocating the work. The difficulty grows surprisingly quickly with the number of people and jobs:
For a workforce of 15 people the number of combinations is huge: 1,307,674,368,000 (that's 1.3 trillion). For hundreds of employees there are more possible ways of allocating the work to people than there are atoms in the universe.
So, if we are trying to do a good planning job and allocate work to the best people based on their skills (or location, cost, availability, etc), we should try all these possible combinations and pick the best. Of course this is impossible so planners use their intelligence, intuition and experience to do the best they can in the (often limited) time available.
Also, in the simple example above, we have conveniently ignored all the other real-world factors that need to be considered by the planner when allocating work: holidays, unplanned absence, customer preferences, logistical constraints, last-minute changes, legislation, etc. These rules, coupled with the sheer size of the problem, make for an extremely challenging planning job.
Conclusion: If you are a planner give yourself a pat on the back - you are doing a tough job. If you manage a team of planners first give them a pat on the back, then get some tools to make their task easier!