You are absolutely right that the dragging spoils dramas but also if dramas begin with a clear cut meaty plotline, they can stretch a show till 38-40 episodes without the show becoming a torture on our senses....think of shows like Friends or Supernatural that ran for so many seasons and just kept getting better with time. If the show is to run for 40 episodes, they must plan out a story that is sufficiently interesting. Like in Habs they could have shown us what happened at Sadia's end, why she made the choices she had and what was the fallout from that choice that we didn't get to see.
OR they could have had an office romance for Bano, the development could have run parallel with Ayet's track.
With Zoya, they could have made it into a comedy sort of track. Amir's family trying to make the best of this new situation in their family with this wife of their son who doesn't hold back with her thoughts, words or actions. It could have been fun to watch Amir's mother rolling her eyes in despair as she loses another verbal bout with this "impossible" girl. But also we could have seen Zoya slowly evolving into a more mature sort now that she finally was out of the shadow of her two elder sisters and charting her own course in a positive way.
They could have continued to show Ayesha's fight to win back her dreams, getting back to studying, maybe Basit getting jealous of the time she spends in the library.
Hell, they could have shown Kareem and the new nurse falling in love and we wouldn't mind. But this boring Talal and his "poor" mother, Zoya's stealing, lying and then turning around and acting like she is some kind of grey character, Fahad acting like a loon and two-faced sneak, Soha being a total bitch only builds on negativity and brings us no joy as viewers.