Here is a decent article. The writer also uses 10 gauge. The issue is why go up against a spec that is at best is debatable? If The speaker’s impedance load goes below 4 ohms at any point, and many do, then the distances listed are certainly too liberal.
https://www.audioholics.com/audio-video-cables/speaker-cable-gauge
https://www.audioholics.com/audio-video-cables/speaker-cable-gauge

