How exactly does practice work?

[marclife]

I'm trying to figure out the best way to utilize this function.

Are the language elements in a practice session chosen based on my weakness, topics that haven't been reviewed recently, or just a random selection of topics I've covered already?

[Luis]

The practice function chooses what to practice based on your weakness (which has to do in part with how long it has been since you last saw those words/concepts).