This is probably the epitome of pre-produced dramas (dramas that were finished shooting before premiere). Why I say this is because this wasn't subject to random audience-induced plot changes or extensions/contractions, allowing the team to stick strictly to their very well written script.

Keep your eyes open because earlier details will foreshadow later events. Everything is introduced to the audience for a reason that has to do with plot/character development later. This is my favorite type of script because the detective in me loves finding clues and remember them when a later plot twist results.

Ironically, I didn't get much sleep during the weekend I binged "While You Were Sleeping"...