Why not use smallcheck?

Greedy shrinking will naturally fail to shrink any part of a counterexample that must relate to some other part of the counterexample. In the common case it can still shrink around one or two simple interrelations (e.g. two numbers that must be equal) and produce something simple enough. When those interrelations become more complex and plentiful, however, a greedy shrinker stalls out all too soon. In particular, I’ve seen this when shrinking things that are more code-like than data-like, e.g. a representation of an opaque type by an AST of its operations.