I can only speak from my experience at the end of January of this year. I walked up about 8:30p and asked if they had any available slots open for just myself and they sent me away because they were all booked up for the rest of the night. Granted, I went late at night but I honestly didn’t think it’d be a problem since I was solo but they apparently do have times where reservations are needed. For my upcoming trip in September, I’m taking no chances and booked a reservation so I don’t miss out this time around. I’m really looking forward to it!