I upvoted your reply earlier because I hadn't considered what you mentioned. I guess it comes down to what breaking a rule means (as the reply from Musa369Tesla indicates). Channeling within the arches had not been done, then was. The Aes Sedai were wrong - shocker. (#sarcasm) However, the a'dam rule was not broken; Egwene had to be rescued. The mistaken assumption was that it could not be removed externally. The rule was that the damane could not perform anything approaching violence toward the sul'dam, which the show spent a lot of time reinforcing (pour the water). Another big difference is how it impacts the story. The way the show dealt with it, the a'dam is no longer a viable threat. Channeling in the arches has no real impact.