My extremely inexperienced two cents for what it's worth...

I understand the reasoning behind having safe words given that you are putting your complete trust into someone which is no easy feat. It makes sense to have a way out if things get too painful/intense. I might say "no", "stop" or just beg for mercy in general but not really want things to stop though. I think given that a Domme might push a submissive to the edge they even expect to hear something like "no" or "stop". As a submissive you should not rely on those types of words ending the session. But, if I was suddenly experiencing a pain, muscle cramp, etc. not at all related to the session play and I needed things to stop of course I would need a way to communicate that. I would think I could just say that, however, and the Domme would stop. To be a successful Pro Domme I imagine you have to be intelligent and skilled enough to read people, even those you might not know well.

Unfortunately, some people don't even know themselves, so where does that leave a Domme as in the situation you explained Cheyenne. That was clearly not your fault as he didn't really know his limits and ego got in the way. I think open communication is a good idea. That's not to say having code/safewords is not a good idea. People might prefer them so they don't kill the mood by becoming all conversational. Then there are those situations where someone might want to session without a code/safeword so they can feel really really out of control.