Planning Mark 1: Doing a Prediction in a Gantt Chart
So let’s try it out, bringing it all together!
In her planning meeting, our baker remembers her Management 101 class back at university. Using a Gantt chart she wants to respond to her customer’s need for planning with exact dates and delivery schedules.
Betty even does a forecast and estimates how many orders will arrive when. How many in summertime? Which types of bread? When will we hire people?
Betty invests weeks into this planning, and at the end her Gantt chart is very detailed and a lot of TLC went into its preparation. The level of detail is astonishing! For example, it tells her exactly that 3 months from now she needs to buy 10 kg of sugar! So proper planning = “Gantt chart”, et voila:
And then, reality kicked in. Even though Betty the Baker was super motivated to follow the plan, things happened. One day, the sun was shining, so she spent half a day eating icecream with friends. Some of the bread-baking jobs took a little longer, because the yeast wasn’t fresh. Another day, the oven took a little longer to heat up in the morning. So after just 2 weeks, she was dangerously behind schedule and ended up with a lot of angry customers.
Plans are things that change.
Fujio Cho, Toyota honorary chairman
The harder she planned, the more her plan seemed to fight back on her. What happened? First of all, the plan was based on many guesses and assumptions. Even though each had only a tiny degree of uncertainty, all of these added up – until the nice plan was nothing more than “asking the crystal ball”.
In addition to that, whenever human beings are involved (check on the progress of baking robots…), these two dynamics are at work:
- Imagine you know a task can be done in 45 minutes, but the plan says 60. You finish a bit early and thus “won” 15 minutes…you rock! Time for a quick coffee break, you deserved it! Funny how w never seem to get around to starting the subsequent task earlier. This behavior is called Parkinson’s law, it’s not being lazy or stupid, just…human.
- Now let’s assume you work on a 60 minute task, and the elders of the planning put a safety margin of 30 minutes behind it, behind the subsequent task is super important. You have to be on time! When would a smart person start? Right, at the very last possible moment, and since it’s a 60 minute task – every sane person starts 30 minutes later than the original plan said. This is called the Student’s syndrome, which unfortunately isn’t limited to actual students.
…all this led to Betty’s plan being outdated the very moment she conceived it, but it’s not her fault. In fact, the normal due date performance looks something like this, showing how the vast majority of tasks is always late:
There must be a better way!