One of the great things about DirectAccess is that all of the connectivity settings the client computers need in order to connect are contained within a Group Policy Objects (GPO). This means that you can turn new client computers into DirectAccess-connected clients without ever touching that system. Once configured properly, all you need to do is add the new computer account to an Active Directory security group and, during the next automatic Group Policy refresh cycle (usually within 90 minutes), that new laptop will be connecting via DirectAccess whenever outside the corporate network.
You can certainly choose not to pre-stage anything with the GPOs and DirectAccess will still work. When you get to the end of the DA configuration wizard, it will inform you that two new GPOs are about to be created inside Active Directory. One GPO is used to contain the DirectAccess server settings, and the other GPO is used to contain the DirectAccess...