Earlier quoted context omitted.
It is my experience that there is absolutely not predictability in learning from the past unless you are doing exactly the same. For something like an agency that are hired to come up with something else thats normally not an option.
The idea that each project we tackle is unique and a special snowflake is an illusion. In reality, most of the factors that influence the outcomes are exactly the same. Same team, same knowledge, same approaches, same psychological biases, same methods, same politics, and so much more. Those are the things that influence timelines most; not the project itself.
It's not that it's unique it's that the problems that arise in them are unique.