"It takes four days."
That means "it takes a period of 4 days"
"It takes 4 days"
When 間 is used, usually it refers to an effort or an activity that is continuous and non-stop process
My question: "It takes four days..." before something happens after not continuously happening OR "It takes four days..." duration for happening, i.e. "It takes four days for the parcel to arrive." vs "The operation lasts for four hours." ?