How long does it take to prepare for a Green Belt?

The durations you find vary by a factor of ten, and that is normal: they do not measure the same thing. Some count training hours, others the total time between registration and the exam, others still include a project to run in a company. Comparing those numbers with one another makes no sense.

The useful question is therefore not "how many hours", but "what is my preparation made of". Three components add up, and they cannot be traded for one another: understanding the method, knowing how to answer an exam question, and — depending on the body — running a real project.

The third is the one that dictates the calendar when it is required. An improvement project run seriously is counted in months, not weeks, and that time cannot be compressed: it depends on a real process, a team, and the time an improvement takes to become observable.

The Green Belt syllabus is not long. It fits in about thirty tools, most of which can be explained on one page. What takes time is the move from "I know what a SIPOC is" to "I know a SIPOC is needed here, not a VSM".

That switch is not obtained by rereading. It requires being put in a situation: a question, several possible readings, a decision to take. That is exactly the gap between revising a glossary and answering an exam, and it is where the difference between a three-week preparation and a three-month one is decided.

The second lengthening factor is statistics, for those who never do any. Not because of difficulty: the calculations asked for are mechanical once the formula is known. But a practitioner who has not handled a standard deviation in fifteen years needs several sessions before the vocabulary becomes familiar again, and that warm-up is always underestimated.

What works best comes down to little: short, regular sessions rather than long, spaced-out blocks, and a mock test at the start rather than at the end.

The early test is counter-intuitive and it is the most profitable piece of advice. Sitting a quiz before having revised gives a low score, which is unpleasant, and a precise map of what is missing, which is worth several weeks of blind revision. The same set sat again three weeks later measures real progress.

The rest consists of not revising what is already acquired. It is the most banal trap: you reread what you understand well, because it is pleasant, and you avoid the topics that resist. A record of your mistakes by topic removes that temptation in a second.

The arrangements change from one body to another, and they are what determines the calendar: length of the exam, pass mark, open or closed book, project required or not, validity limited in time or not.

That point is checked before starting to revise, not after. Finding out along the way that a technical file is expected shifts a preparation by several months, and no revision effort makes up for that.