Have said that I watch the show in my selective way.
So anyways, coming to point, I happened to watch yesterday's episode, and I can definetely say that this was pre-planned.
The FBs clearly indicates that, especially where they litteraly show Shagun jumping from terrace to 5th floor's balcony, that balcony was the same as where DT and Ani took one selfie the day of shooting.
Where they show Ishita locking the door at Manoj's and going to sit back, that was obviously shot the same day as it was on continue.
Where they show Abhi-Shagun scene after he send Raman and Mihir away, that was the same exact spot ground and position of ambulance, that day they just had cropped Abhi-Shagun scene and only shown Ishita Mihir and Raman going home.
I have my doubts on the 'sitting lady crying' FB, and The sindoor one too might have been added later, but the rest were all shot same day of their actual scene.
Besides, I had 'predicted' that Shagun would have been catched on the below floor đđ