Many years ago, in a previous role, I opted to join the consultancy team, specifically to work with a new product due to come out at some point in 2001. At the time, it was available to those that worked directly with Microsoft on projects. I was working at the Microsoft campus in Reading, UK, and for the project I was on got access to nightly builds which would become SharePoint Portal Server 2001, as that project expanded I got to do the same for SharePoint 2003 as well. I would install and test it, repeating that cycle almost daily.