Approximately 1 to 2.5 hours, depending upon what we’re designing and how many people attend.
Sorry to be vague, but the truth is that products such as albums can take a little longer to design, and meetings can run for longer if there are several people placing separate orders (e.g., Grandma, Big Sis and yourself).
This is one of the big reasons why we recommend not bringing kids to a Big Reveal. They’ll usually be perfectly happy while we’re all looking at a slideshow of the pictures, but will quickly get very bored when we all start getting excited about little design decisions.