At the end of the day, you can't force a kid to sleep. Trust me, I tried. A lot.
I was able to _make_ him take a nap, at great cost, but he just stayed up at night. He slept less hours total, when he took the nap. Now, when he sleeps early or more, it's generally a sign that he is extremely stressed and we are about to start seeing major symptoms.
We have often desperately tried to get him to sleep more, because we've been concerned he wasn't sleeping enough. I go back and forth on this. But at the end of the day, I gotta say, there's a limit to how much you can "protect" sleep, even if it's crucial.