Following an exchange on another thread, I was asked by @Hudson555x about using the playlist, which I do extensively. I mentioned in that thread that I had not long ago had to rebuild a segment and that preserving the playlist had been key to making it easier. It occurred to me that in the rebuilt piece I had done all the object animation with Shotcuts new key-frames, mainly Size&Position and Brightness, but also using them working in tandem with filters like Crop and Mask. In the previous version I had made the object animations in an external program and used chroma-key to integrate the videos in SC. In addition, I could not have animated video inserts in the way that I am now able 
So by way of explanation of why I find playlists so valuable (many individual elements) and as an example of what can be done with key-frames, a few PNGs, several layers of video and a little arithmetic, I’ve posted the rebuilt segment below. I have muted the narration but otherwise this is the finished article.
P.S. - is anyone else using SC to produce videos in a similar style? It would be great to share ideas & tips if anyone is.