The principle of just-in-time (JIT) consists in supplying the customer with the number of products he requires, when he wants them, where he wants them, and to the quality and cost standards he has set. This implies, first and foremost, that the entire production process is subject to customer demand (internal or external).
In practice, this principle leads companies to "do it fast to sell it fast", as customer demands become increasingly varied and their delivery times ever shorter. As soon as demand is received, production, or at least assembly, has to start.
It is also a question of preserving margins in the face of new forms of competition. The company must therefore seek to "produce at the lowest overall cost", without reducing the quality of products or services expected by its customers. The only solution will be to "get it right first time", thus ensuring customer loyalty.
However, a cursory glance at history shows us that people have always known how to produce "quality objects". In today's industrial context, what differentiates us from the past is the very definition of quality, on the one hand, and repetitiveness and speed, on the other. These constraints lead to the generation of deviations between the intended target and what is actually achieved. The problem is to minimize and control these deviations.
The key to success is, of course, the individual: "nothing is possible without people". It is therefore essential to ensure that they participate and adhere to JIT concepts and, in particular, to the principles of continuous improvement.
Just-in-time means eliminating all waste. It means that "if you don't need something now, then don't do it".