It depends on your objective. The process you describe is excellent for achieving technical mastery. Less so for compositional mastery, but it can still be educational to see written parts up close.

What it wont prepare you for at all is impovisational mastery and just jamming over some chord changes.

Also, I don’t know many musicians who would completely ignore technical exercises like scales, chord voicings, and arpeggios.

So, it depends on what kind of musician you’re trying to be.