  By a "scheme" of a musical canon, we mean the time and pitch displacement of
each entering voice. When the time displacements are unequal, achieving
consonant sonorities is especially challenging. Using a first-species
theoretical model, we quantify the flexibility of schemes that Renaissance
composers used or could have used. We craft an algorithm to compute this
flexibility value precisely (finding in the process that it is an algebraic
integer). We find that Palestrina consistently selected some of the most
flexible schemes, more so than his predecessors, but that he by no means
exhausted all feasible schemes. To add support to the model, we present two new
compositions within the limits of the style utilizing unexplored canonic
schemes.
  In the Online Supplement (attached via Papers with Code), we provide MIDI
realizations of the musical examples and Sage code used in the numerical
computations.
