Optimal learning and inflexion points.
There's a level of challenge where the most learning takes place. Not only is learning maximized but self-satisfaction/pride is also high. Staying near that level is a goal.
Sometimes you get stuck or fallback, i.e. hit an inflexion point; at that point you need to learn meta-skills beyond the material to keep moving. Not developing those meta-skills can lead to brick walls later like in college (study? what's that mean?)
No matter how little or much they learn, by nature they will always continue to learn. But with no push and no challenge (or the converses) they can degrade skills/abilities like creativity, curiosity, excitement, perseverance, self-motivation, drive...
So, for me, I want to be a guide to help my DS move at his ideal pace and to coach and support him past the inflexion points because just on the other side is more of what he really wants despite whatever temporary barrier is keeping him back.
Of course that is just my idealistic philosophical perspective and when the wheel meets the road, MMAV (my mileage always varies.)
