Well, my recruiter callback ratio is likely 1 out of 5, despite having a very VERY niche profile: a PhD focused on NLP for creative text generation, especially in video games, and a prior career as a game developer.

Needless to say, I've only focused on roles that fit that narrow profile. One of the recruiters that contacted me didn't even know I worked in games, despite it making up the bulk of my work experience (including as a lead developer).

Considering how closely I match this narrow profile, and the number of people that likely do, it's weird how low my callback ratio has been.