My observations are not necessarily in order. This is true for this first lesson because it came in the later part of the episode.
Making mee sua takes a few steps. Along the way, the apprentice botched one of the steps. If I remember correctly, it was the part where she was supposed to place the dried noodles on top of each other and she didn’t do it properly.
So the master explained the rationale behind the way they placed their noodles. Apparently, the strand of noodles had to be placed perpendicular to each other so that it was easy to pick up later.
This may sound easy but as the master said every step of the process is important.