I really liked Ruby Sunday - and I didn’t, in fact, bump too much on her being relatively fully formed (she needed an opportunity, not a character reset). What was missing - in a truncated season - was her and the Doctor interacting together. Their relationship didn’t really develop.

Agree. I liked the arc with her birth mum and foster mum and I bought the Doctor and Ruby getting along like a house on fire... but it feels like their relationship simply WAS, rather than evolving. I just needed maybe one chat per episode that might put a pin in their relationship development.