"Common practice" is a chimera, a vast and convenient reduction that has seen its chronologically early third chopped off by partimento studies and its later half chopped off by the waltz, the polka, and the symmetries uncovered by neo-Riemannian studies. What's left? Music for the bourgeoisie (that's the educated middle class) in barely two generations covering roughly the period 1780-1830 (with possible extension to 1850, in the "mannerist bourgeois" of Mendelssohn, Schumann, and A. B. Marx). This is the period of the turn from patronage to entrepeneurship. . . . See how easy it is to fall back into comfortable narratives? It was the period of the turn from patronage to entrepeneurship in Vienna -- a shift that had been accomplished in the wealthy, trade-oriented commercial cultures of England, Scotland, the Netherlands, and a few other countries starting already in the 17th century.