The Shift Reservations step lets a user pick their own time for something that has to happen on a date, such as an interview, an orientation or a training session. You create the shifts the way you always do. The step simply lets the people on it reserve one.
It is a sequence step that shows the user a list of available times and asks them to reserve one. The times are real shifts on a real opportunity, so everything else about them works exactly as it normally does: the shift appears on the user's schedule, they get the usual reminders, and they check in and out as usual.
What is different is who is allowed to reserve. Normally a user can only reserve shifts on an opportunity they are assigned to. Reaching this step gives them permission to reserve from the opportunities you name here, even though they are not assigned to those opportunities.
Typical uses:
First, create the opportunity and the shifts people will reserve, exactly as you would for any other opportunity. Each session is a shift with its own date, time, location and number of spots.
Then build the step:
Entries are reusable. One "New User Orientation" entry can sit in as many sequences as you like, and editing it updates every sequence that uses it. You can manage them all from Manage fields, or from All fields.

You decide. Two settings control it, and for most steps you only need the first.
Shifts they must reserve is how many reservations it takes to finish the step. Usually one.
Most they can reserve at a time is a ceiling on how many they can hold at once. Leave it blank and it matches the number above, which is what you want almost every time. Its job is to stop one person reserving every available session. Raise it only if you want to let someone hold an extra slot, such as a backup. Cancelled reservations do not count against it.
You choose, under This step is complete when. There are four options, and they get progressively stricter:
The last two are worth thinking about. If you pick them, the step stays open between the reservation and the session itself, which can be weeks. That is usually correct for a training you must actually attend, but it does mean the user will see the step sitting on their list in the meantime. Their reserved time is shown on the step, so it is clear why it is still open.
They sound similar and do different things, so it is worth being precise.
Reserve by (days after reaching this step) is a clock for each person. It starts when that user reaches the step. If it runs out before they reserve, they can no longer reserve and an administrator has to reopen it for them. Leave it blank for no deadline of its own. The step's own due date still applies either way.
How far ahead to show slots bounds the list of times everyone sees. It never expires anyone. Use it to stop a monthly orientation offering sessions eleven months out. You can show everything upcoming, only the next few months, or everything up to a fixed date.
The step appears on their sequence with a Reserve button. Opening it shows the available times, how many spots are left on each, and how many they still need to reserve.
They pick the times that work for them, review the selection, and confirm. After that the shift behaves exactly like any other shift they signed up for: it is on their schedule, they get the reminders, and they check in on the day.
If they cancel the reservation, the step reopens so they can book a different time. They do not need to ask an administrator to reset anything.

Yes. Open the person's sequence and click View on the step. You will see the entry's settings, where they are against the required number, and each time they have reserved with its status (Reserved, Awaiting approval, Checked in or Completed).
From the same screen you can set a custom status, add notes, and set a completion or expiration date, the same as any other step type.
By default every administrator in your organization can. Under Site access you can link an entry to one or more sites, which controls which site administrators can see and edit it. Leave it unlinked to keep it available across the whole organization.
Usually yes. Creating one opportunity to hold your interview, orientation and training sessions keeps them out of the way of the opportunities people browse and sign up for. Set that opportunity's visibility to Private so it does not appear on your recruitment page, and the Shift Reservations step will still let people reserve from it.
Reserving from this step also adds the user to that opportunity, which is what puts the shift on their schedule. If you would rather they did not see that opportunity in their own list, you can hide it there.