This depends on the company. Before every letter drop deadline, we will inform you of each company's policy. You will receive an email from the Career Services office if you are on a closed list. Also, the Interviews and Bidding page on TuckStreams indicates the closed lists for which you have been selected. If you are interested in the company and want to be on the interview schedule, you must bid for a slot.
Companies have a limited number of closed slots on their interview schedules.
With so many great candidates available, it is very difficult to choose from among them. If you are selected as an alternate, you will be notified via email. When someone drops off the closed list, alternates fill those slots. If an invitee declines before the bid, you will be notified and can accept the invitation via TuckStreams. If you are not notified and you want the interview, bid for it.