I don't know how to say this any more clearly - I am not proposing severing as an alternative to imprisonment, guards and eventually, execution! I am prosposing it SOLELY as an alternative to SHIELDING. With shielding, you have to work to maintain that status, and with any disruption of your efforts, the prisoner can abruptly revert to his or her default status of "dangerous channeler." By severing them, all efforts (or at least an exponentially greater proportion of them) can be turned to guarding against external threats such as a rescue. Not only that, it forces the other side to make the effort to restore the captives when they are rescued. If the bad guys have a channeler handy who is capable of Healing severing, they still do not have any advantage that makes shielding the superior tactic.

If your point was to argue for execution over stilling, well that goes without saying. I'm more of the "cut them down on sight like rabid dogs" school of thought and much prefer the Children of the Lights' response to discovery of Darkfriends to the Aes Sedai treatment of Ispan. The only drawback with summary execution is the finality and the unlikelihood of reversing a mistaken sentence if the suspect is later discovered to be innocent. Stilling, however, is a perfectly acceptable technique to restrain suspects until their guilt can be absolutely proven at a trial. Thanks to Nynaeve and Flinn, it is now possible to restore the ability to the severed captives, for good if they prove to be innocent and arrested by mistake, and temporarily in the case of the guilty if the more obtuse Aes Sedai insist on going through the formal procedures of an "official" stilling before the execution. What is more, severing will free Black sisters of their Oaths, rendering interogation much more practicable.

The fact that the bad guys could reverse such a condition if they rescued the prisoners does not change one iota the practical advantages of severing over shielding.