That's an interesting comment as well. I'm not a fan of the 'word insertion' editor based challenges either.
Also on the best practices I found issue with the 'highlighted' area in which you are supposed to edit. I prefer the the more freeform of editing as in earlier challenges. You may screw up the example code (you need a reset button) but at least you can experiment.
And one other point I am finding with the more advanced topics like best practices is that the information flow seems to be asymtopically trending to zero. As the subject becomes more advanced, how to keep the challenges also at appropriate level, and not just small changes in the code to indicate understanding and proficiency.
The approach has worked with the beginner levels and understanding on syntax, but when tackling what is much more about the semantics it appears to be a harder problem to crack.
I suppose I liken this to the Stanford University iOS course. If you follow through and do all the examples you are really 'cooking on gas' with your understanding of iOS by the end of the course. I don't think I can say the same about the level of understanding after doing the iOS course here. (They cam across as more a refresher, and that why I was doing them).
Anyway, hope that is some helpful commentary.