The Spurs haven't spent many offseasons as a player in free agency. This summer they had 10 players become free agents. With Aldridge making his decision to come to San Antonio, the Spurs have probably finished making their major moves and have emerge as the league's clear winner this summer.
The Spurs may lack experience in the free-agency, but they developed a great game-plan (perhaps as simple as pointing to the results they've seen and the reputation they've garnered over the past 25 years,) got a good night's sleep and aced the test -- even if they had to wait longer than they thought for the results to come back.