Watch the Soloing Study #2 online guitar lesson by Jon Finn from Modal Rock Soloing
Here the chord progression moves around a little more than the others. Compositionally, it's done only to add variety. All the chords come from the key of A, and Jon takes a moment to explain that. Keep in mind that when songwriting, go with what sounds good, not what the rules say. This process described here is meant to help figure out what's available for improvisation after the chords are written. Practice this process until it becomes internalized. But it's also important to experiment outside of those limits too.