You can learn more and learn fast by actualizing it right away the moment you hear or see the instructions.
Lazy people thinks that once they hear it and saw it then they already learned it. But when the time comes and they need to actualize... they completely forget everything. Even if you know the details, if you didn't try it then you really don't know it. It is like watching a cooking show on how to cook a lemon chicken, you can memorize everything that was said on the show, you can memorize the whole recipe but if you didn't try cooking it then you still don't know it. Because you will not know the taste, you will not know the timing, mixtures etc.
Just like your math teacher teaching a new lesson... you can copy the lecture but if you will not solve problems by your own then you still don't know it. You may have the notes, you may memorize the formulas but if you haven't solve any problems then you will not be able to solve it during the actual exam.
It is better to learn by doing because once you do it right way... you already know what to do next time. You will never be lost, you can do it faster and better.
You can also learn even if you didn't hear anything from someone, you can learn by yourself by simply doing it. You can make mistakes or you can make it right the first try. If you made a mistake, well at least you will have a feedback and you will know what not to do next time. Applying is simply learning, you just need to do it even if you are not so sure that it's going to work. If you will not try it then you will remain an ignorant forever, you are just pretending that you know it.