That depends mainly on your ability to accept. Generally no more than a week. Because there are only a few snacks in snack car. Even if you study for half a day, you can review several times a week. Snack car's main training place is just knowing how to match ingredients and so on. As for proficiency, it should be strengthened in future practical work. Joining snack car is very expensive now. And everything is delicious without it. So it's better to find a home and not join. Snack car also covers technology. I personally recommend Jiangxi Xianghe multifunctional snack car.