In the introduction to his 6 Duetti of 1759, J.J. Quantz describes in detail the usefulness of practicing and playing duets over that of concerti and solos. He tells us we will
As a teacher I have found the playing of duets in lessons perhaps the most useful tool for teaching and implementing the techniques and stylistics associated with baroque repertoire. These recordings allow you to practice in private, improve your technique and be better prepared for your ensemble playing.