Jeff, after reading this entire thread carefully, and the variety of responses, I am inclined to agree with your original point, of a safeword not being needed, to see signs, that tickling has to stop, either through physical signs, or something else the lee says or does.
To me, while I understand the concept of "safeword", it doesnt seem like that should be the only protocol for tickling to cease. As I read the thread, I kept thinking to myself:" Hmm, what would happen if I was the lee, (As I am a switch , both ler and lee), and the girl was giving me an unmerciful tickle, and, I either forgot my safeword, which I'm sure can happen in circumstances where one's brain might freeze up, or, perhaps, I was laughing so hard, and so hysterically, and all my brain was thinking about was the tickling, where I couldnt get the safeword out. You make an excellent point. The girl keeps tickling me, and, I'm gasping for air, and she goes:" Nope, Mitch, tickling continues, because you didnt shout your safeword." Granted, it would seem that most lers who saw signs of serious physical diress, would heed the warning signs, and stop on their own, but, you would also think that in that circumstance, a safeword shouldnt be needed, to see, that the ticklee either has to rest, or the tickling has to cease, at least for the time being.
Do I understand why tickling partners use safewords? Absolutely, and Myriads post makes an excellent point about that. Are they, or should they be necessary, if all other signs are there, from the lee's reaction, that tickling has to stop? No, they really shouldnt be, so, I do agree with you, that they arent really "necessary" if other physical signs are there.
Very interesting discussion, and a good spectrum of replies.
Mitch
One other point I wanted to make, from my ler side. I am certain that if I was tickling a girl, and, even if we had established a "safeword". If I was giving her a good tickling, and saw that there were physical signs there, where she was really in diress, I would very likely stop, even if she didnt shout her "safeword", for reasons of physical safety.