30 Teams, 82 Games, Slightly less than 6 Months

The 30 teams are divided into 2 conferences with 15 teams each. Each conference is then divided into 3 divisions, with 5 teams each.
An individual team will play each team from the opposite conference twice, totalling 30 games. Teams in the same division play 4 times every year, totalling 16 games. Teams in the same conference, different division play 4 times, except two teams from each division that play 3 times. Which teams play just 3 games rotates fully every 5 years. For example, the Oakland Warriors play the Utah Jazz in Utah twice four in every five years and one year they only go to Utah once. Conversely, the Utah Jazz play the Warriors in Oakland twice four every five years. (This minor detail has added tremendously to the tediousness of this problem.)

Full Season Breakdown

NBA Divisions

Red is Western Conference, Green is Eastern Conference