Keep in mind, not all dramas less than 40 episodes are great either. I am currently watching The Love Lasts Two Minds which has 36 episodes and it has too many cliches; it just is not for me. Some of the best dramas had over 50 episodes and people were/are hoping for more. Then there are those who got everything they desired in 24-40 episodes.
Although it is true that long dramas can drag out episodes unnecessarily (for example Legend of Fuyao, Ashes of Love, Princess Silver and may more), I find it better to just separate the drama into seasons*. If you aren't up for long dramas, don't force yourself. Try not to look at the number of episodes in the drama. Read the description, watch the first few episodes, (once they've all been aired) skip to the last few episodes, read comments, reviews and decide whether or not to commit yourself to the drama.
