How many pages/how to narrow down?

From your other work, take the 2-3 next best projects and develop 1-2 pagers

This is good advice. If a project isn’t “complete” in the traditional I.D. portfolio sense, it doesn’t mean it’s worthless. What if you’re a brilliant metalworker and you spontaneously made a table one day, without the usual “design process,” and you’ve got some great photos of it? Might as well have it on hand.