Reading these posts I must say it has also been my own philosophy that no matter how much you are ragged on, only you can decide to quit. You don't give away that power.
An anectote however. There was an Aikidoka who was being a compliant uke for a mate who was asking one of the instructors to check his technique. Unsatisfied with the sankyo as demonstrated, the instructor himself applied a sankyo on this compliant uke, taking him down at an extremely painful angle. He then offered to show it again, and this time ukes shoulder was nearly dislocated as it crashed to the mat.
Uke, cheek scrunched against the mat, noticed kancho sensei across the room slowly rise, and come over and offer to demonstrate same technique, with the instructor as uke. Kancho Sensei made the point that once you apply the lock you do not release it until the pin. Instructor was slapping his thigh frantically, and soon was on the mat, still slapping for his life.
Kancho then offered to show how this worked in the case of a nikyo, and the pain seemed to be more extreme than in the sankyo. A long time on the mat, instructors hand flapping like a beached fish.
By way of demon-stration, Kancho then performed an ikkyo on instructor with the same efficiency, seldom does one see an ikkyo that is so painful even before the pin is made. Instructor 's feet were off the ground.
Then Kancho asked the two original students, 'Understand?' and they nodded and Kancho walked away and they went back to practice.
The moral is that if such a Kancho sees the abuse, he might deal with it without letting on. This is the kind of dojo you want.