Part of being depressed is you don't even have the will to resist being treated in a way that you don't like.
In fact, I'd say that feeling powerless against conditions that you don't like is the core of what depression is.
It's why someone who is depressed doesn't feel like doing anything, because they feel like no matter what they do nothing will ever change so nothing they do is ever worth the effort.
Just mildly uncomfortable .. for a period of time longer than one would be willing to tolerate.
Something like being at the dentist when you have many cavities in your teeth.
You can tolerate one or two sessions. But the idea of doing it every day for two weeks straight is unbearable enough that you decide on the third day to report feeling well.
Eg. "We'll poke this red hot poker into you 10 times to cure your depression"... Many painful screams later... "So, is the depression any better now, or should we do more treatment?".. "Yes, yes, I'm pretty much cured!".
How can we be sure that this 'torture effect' isn't whats being measured here? Especially when the treatment appears to have unpleasent side effects, and the success of the treatment is measured with patient feedback...