It's funny (and also sad) how science "teachers" all over the world simply make kids cram up facts in their little heads instead of doing actual science.
It depends on the types of classes. My labs in chem 311 are worth 40% and the marking is strict strict since it's based on determining unknown samples. My labs in chem 351 is only 20% and the markings is based on understanding the theory of the reactions in my reports.
You need to understand reactions first before you can apply them in real labs. Otherwise, you just follow the procedures in a brain dead manner.