Let's start from the very beginning... The first step in a professional kitchen would be learning the rhythm, the pace and flow, where to stand and where not to, what to touch and what will burn you, cut you and hurt you. This takes time and often recovery.
Step two is learning the absolute basics. This takes as long as it has to. It depends on someone’s focus, age, drive and demanding girl or boyfriend.
Step three is learning one by one the various kitchen stations: pastry (desserts), cold kitchen (salads and cold dishes), entremetier (vegetables), poissonnier (fish & seafood) and saucier (meat & sauces). Cooks are transferred from one station to the next for a minimum of 6 months and until they can prove they can deliver. Once they have done time on each station and if they are still standing, they are ready to become Chef de Partie. They fill in on any station when someone is sick or just decides “no more” and keep a close eye on everything being done. They are basically a baby Chef learning key elements of management, costing, ordering and helping to run the flow of both information and work, assisting like a fireman to extinguish problems.
Only when you have really mastered being a student can you dream of being a teacher and after a few years as Chef de Partie you know what you are talking about and are ready for a Sous Chef position. Sous Chef is pretty much the same job but instead of helping, the responsibility is now painfully entirely yours. Sous Chefs need to be masters at getting things done, no excuses, no compromise, no procrastination, just done and done well. You are the extension of the Chef, the go-to guy, the person keeping the boat floating.
At the very top of the pile is the Chef de Cuisine. This guy has done all of this and either by years and years of hard work or great timing when the person on top passes out from exhaustion, finally gets a shot. Where the Sous Chef is like Luke Skywalker, the Chef de Cuisine is like Yoda. They need to cook beautifully, answer any question, catch mistakes before they ever happen, deal with happy and unhappy customers, be the hero and the villain, they do it all.