There are many ways to use the JustinGuitars site to learn/practice, songs included.
The last few months I hit a brick wall feeling that I was not moving forward. I had been practicing songs using Justin app and Gibson app on a daily basis, 2-3 hours a day, doing a bit around scales and some blues stuff. And there you have it I was going round and round the same thing making small improvements but not really learning guitar or variety on it.
So my take is learning songs to play is great if that is what you want to do but that in itself can be limiting in several areas. It means you learn what you learn in songs, it may restrict technique and versatility, and a guitar student will not necessarily understand the guitar as a musical instrument or learn how to improvise and be creative.
I am not sure I have a complete answer to this, often called the intermediate wall, and as I understand it the point where a lot stop playing. However I think it’s the point in a learning journey where a quite structured approach is required that results in a very good grasp of the guitar that brings together chords, scales(major, minor, pentatonic, blues, a few others), keys, technique(strumming, finger style, rhythms, articulation, soloing), a basic understanding of music theory.
I now think that a structured approach that addresses all the above and brings them together is probably what I need to adopt. So for example in the past i looked at the CAGED system briefly but never fully understood it, but over the past few weeks I revisited it and am working through exercises to embed it. The great thing I find with CAGED is it addresses several areas simultaneously, the guitar neck, chords, and there relationships and where they can played on the neck, scales and how chords are built from them, chord tones and how they relate to Root notes and each other, and ear training. The exercises I am using at each stage put it into practice chords, chord tones, and build through scales by playing musical compositions that grow in complexity gradually, they also address technique and soloing as you progress. It is early days yet for me with it, but I think my understanding and learning curve is now starting to improve.