It's a difficult subject.
I often drop dramas even highly rated, just because I wasn't in the mood for it.
It's all "happen-stance", whether it clicks or not. Depends on many factors.
For instance, I dropped Signal because I just got bored at the time with such serious dramas. I preferred a 7.8 comedly fluff cdrama over a 8.9 kdrama seriousness about homicides.
But I do continue to re-evaluate. It took me a year to finally finish My Mister, I started and only watched 2-3 episodes before dropping. It was too heavy for me. But I'm glad I finished it few months ago, for obvious reasons.
So it depends on your mood. And it's beneficial to take breaks from TV :)