I agree somewhat. I think that I, personally, learn best when I have some challenge I can't solve yet, and learn skills to solve it. An example: In Calc, my teacher was teaching volume of some function rotated around the axis. Integrals. After covering it for a day or two, someone asked, what is the volume of a torus? My teacher took this, and spent a week solving the problem, introducing techniques (like trig substitution and integration by parts) as needed. On the last day, be bought donuts for everybody.

The week after that, he went over all the concepts again, but seeing the problem, then seeing the way to solve it seems better, to me.