The Spurs core is super old though. They basically need to do that because they'll completely gas out before the playoffs begin if they don't.
DeRozan, JV, and Ross are at average age of like 23. Lowry is getting up there a bit but is still only 27 and has shown no signs of wearing down. These guys are young and have great gas tanks.
We still have like 20 games left in the season. Rest these guys closer to the actual playoffs (the schedule is hilariously weak in the last few games too so we shouldn't get hurt). It's too soon to take the foot off the gas.
I'm not saying that they shouldn't go 8-10 deep. I'm just saying that Casey needs to be smarter about it. Nobody on our 2nd unit is as good as Ginobili. The offense completely disappears when they take all of DD, Lowry, and JV off the floor.