回答

・slip up (at the final stage)

例句
As to my junior's business trip plan, I would like to say, " Your plan always slips up at the final stage, so I want you to give it a second look."
關於我後輩的出差計劃，我想說：「每次行程安排總是不夠縝密，請你再重新規劃一下。」

「掉以輕心」，意味著「在關鍵的最後階段缺乏細緻周到的考慮」。"slip up"可以表示「犯錯」「失誤」。

「掉以輕心」還可以用其他表達方式
"fall apart at the end"

有幫助｜0