fitMarks picks a stride that divides the interval count, so the last label lands on the end rather than short of it. Five marks cannot reach that guard — find() settles on a divisor first — so the check carries a six-mark case that does. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01K1moruzue2kTJd3uVisgNk