A candidate went through three rounds with us, and all three sets of notes said some version of "solid, communicates well." None of the notes mentioned what we were unsure about, so each round quietly re-confirmed the last one's good feeling instead of testing anything. Now every round ends with one written doubt the next interviewer has to probe. Half of them resolve fine. The other half we'd have hired on momentum.
Worth checking what your own process does with an unwritten doubt.