It's not a fair comparison to suggest the NBA is even remotely close to the physical toll a game of Rugby takes on a body. If nothing else an NBA game goes for around 48 minuets, and has free substitutions, a typical NBA player doesn't play more than 20 to 30 min a game. The physical toll on the body generally increases at an increasing rate, so playing 40 min over 20 min would more than double the required recovery time, and 80 min would be even more than double the recovery for 40 min. Then add in that the NBA is largely non-contact, and that the NBA make extensive use of load management.
Load management probably isn't strictly necessary, but it's a good policy when you have depth and don't lose too much when you use it.