Bini im not so sure that Imli turning negative benefited that much to show. In that time there was drama about KN killing Chakor then Banaras track, and after that Chakor killing KN. The real face off between Imli and Chakor happened after 5 years leap and even then we had Suraj's memory loss, RV presence, villagers revolt, etc. There was always lot off factors affecting story besides her. Or at least there was many instances of her not acting directly, like manipulating Suraj during his memory loss. The second half of after five years leap which was supposed to be elections fight between sisters was mainly concentrated on Suraj-Chakor-RV. Don't need to say anything about climax and how it ended.
She boosed over RV but vilagers knew him from before and I think it was expected he will backstab her but it happend to late. Although he was acting as mad man so it was more understandable she orders him, slaps him etc.. now people don't know anything about Karan and from first meeting she is boos. I don't think they find it interesting. Rivalry between sisters can work and works with TRP aunties but only when both sides are equal and there is more open fight especially when that rivalry and enmity is old one. Right now it's nothing like that.
What I want to say is since it was never just rivalry between Chakor and Imli but lot of other factors that kept story moving we can't conclude how much it benefited to show. Right now when main focus is Imli trying to harm Sukor situation is not at all good. The main theme is ignored, Karans role besides being Imlis partner or better to say helper, is not clear, Sukor are in happy zone and seems like nothing can make them worried for a longer period, everyone are naive and there is lack of logic. In my opinion, focus on Imli is reason why recent leap in not working and I have my doubts it was like that before just it was masked with other aspects of the story and trp audience didn't looked for particular details of story but looked at story in global.