Chickens can be very confusing for a newbie. They are living animals, each with their own personality. Each flock has its own dynamics. We keep them in totally different circumstances and conditions for our different reasons. We manage them differently. Flock make-ups are different. Each situation is unique. There is seldom one right answer for anything chicken that covers us all.
I guess I’ll go into my guideline rant. There are a lot of recommendations on this forum that are guidelines, not absolute laws of nature. Following the guidelines exactly does not guarantee absolute success. Failure to follow a guideline does not guarantee total failure. All the guidelines do is improve your odds. There are no guarantees either way with them.
The guidelines are for people that don’t have any experience with chickens. If you don’t know, you need a starting point. They are intended to cover everyone from Miami Florida to Fargo North Dakota, Perth Australia to Inverness Scotland and everywhere else and pretty much keep them all out of trouble in spite of lousy coops, bad weather, and bad management practices. They are intended to cover someone keeping four hens in a small coop in a suburban back yard and someone free ranging flocks with several roosters and hens raising baby chicks. (Most guidelines on this forum are pointed toward the small backyard all-hen flock) As a result, many of them are overkill for a lot of us. They are generally over the top. That doesn’t mean there is nothing to them. It just means they are very safe for most of us and more than the absolute minimum most of us need.
What kinds of things am I talking about? Coop and run space, roost space, number and size of nests, how to store eggs for incubation, things during incubation like turning and humidity, temperatures for a brooder, feeding them treats, grit, or extra calcium, ventilation and draft protection in a coop, broody hens, integration, and who knows what else. There is no one right answer where everything else is wrong for any of this. There are things that have been found to work for most of us most of the time. And there are usually many different things that work.
How long should you keep chickens locked in a new coop? Are you adding to an existing flock or is it a totally empty coop? Are they free range or will they be locked in a run when they are out of a coop? What are the ages involved, and breeds? What are the individual personalities of the chickens involved and the flock dynamics? In some circumstances with some chickens a few hours is probably enough. In other circumstances a few days will be needed. A week is overkill for most people most of the time but it is also very safe in practically all conditions. If you keep them locked up that long, they are not very likely to go wandering, looking for a home. But there is no guarantee they still won’t sleep in trees instead of returning to the coop to roost. They will practically always return to the coop, at least the immediate vicinity, but they are living animals. They don’t come with guarantees.
Rant finished.