¡Claro que si! Lo mismo aqui.
IMO the practice lessons are underrated and awesome. I mean, while yeah they nominally replenish your hearts, they also re-drill earlier stuff that might otherwise start to drift out of su cabeza.
So much of locking in a language is about immersion & repetition, and it seems to me that stuff like Duo's practice lessons genuinely help replicate immersion.
Anyway, good luck on finding a practice buddy!
One thing I've learned is to not try to hop between Spanish & French, since it's a great way to get it all jumbled up. :S