This is not what I stated, sorry
I said:
- in space X there's two possible actions, like Puzzle + Search
- you have 1 investigator in space X-1
- if investigator from space X-1 moves to X, he has one move step left, and one additional action, so, he either does Puzzle or he does Search, and if he then has to stay there because those element are important to the story, he wastes half of his movement
- if you have 1 other investigator arriving in space X-1 with one action left, he may push the first investigator so that neither of them wastes half actions
Hope it's clearer