What is the generally cited ideal total occlusal convergence angle of taper for a full crown preparation, to maximize retention while still allowing for proper seating?

An ideal total occlusal convergence angle of approximately 6 degrees is classically cited as theoretically maximizing retention and resistance form for a full crown preparation — though in actual clinical practice, achieving this exact angle is difficult, and a more commonly achieved practical range (often cited around 10-22 degrees total convergence) is generally still considered acceptable for adequate retention.