Polished is usually more attractive for the eye. Shiny and reflective objects are more wanted and more desirable. It is the same with the drawings and the sketches. Consequently, the shining objects are nicely looking, but their drawing asks for talent and techniques. The artist in the video explains how to achieve the shine of the drawn objects. Most importantly, you should decide where the reflection is going to be. Afterwards, you should highlight that point and use it as a guide. Use the perspective and see where the shine will fall.
Polished Things Sketches by Nugent
See the tutorial below and listen to the instructions explained by Spencer Nugent.