The transit area, and the side of it a visitor can reach
The transit area is the airside zone past security and border control; a visitor cannot enter it, so a session needs a room on the public side.
Airports divide into two sides. Landside is open to anyone: the arrivals hall, the train station, the hotels around the terminal. Airside, or the transit area, lies beyond security and border control, and only passengers with a boarding pass for that day can be there.
Why it matters for a session
Every session takes place in a room you checked into under your own name, and she has to be able to reach that room. Nobody without a boarding pass can pass into the transit area, so rooms, lounges and sleeping cabins inside it are out of reach. A layover session needs you to walk out to the landside, which means clearing any border check between your gate and the arrivals hall.
Who stays inside
Passengers connecting between two flights outside the Schengen area can change planes without entering the Netherlands. If they cannot or may not enter, because of their passport or ticket, they remain in the transit area for the whole stop. A transit arrangement that permits a change of plane does not normally permit a walk to a hotel. Your airline and the official Dutch sources are the place to check this, well before you fly.
The guide to leaving the transit area works through passports, bags and the return through security. The layover entry covers what is left of a stop once you are out.
The way back in
Walking out of the transit area is only half the trip. The return runs through the departure hall, a security screening and, on a flight that leaves the Schengen area, a second passport desk, and the queues at each of those move at their own pace, which no message from the house can hurry. That is why the departure time belongs in the first message: the reply sets the end of the session from it, with a clear margin left before the gate closes.