I think the idea of using a partner for PE could be counterproductive, UNLESS somebody suffers from premature ejaculation.
I say could be counterproductive, because we are designed to get aroused in the presence of a female. That is the basic of reproduction, survival and continuity of the species. If that female gets naked, or make us naked, and approach to touch our phallus, we naturally start pushing all those vasodilators and promoting an erection. If she touch us, the erection keeps developing until we are ready to grab her and penetrate her.
Doing PE with her, we would have to basically be fighting this behavior the whole time, to the point that we could potentially train our brains to not get aroused with a woman. True, we could develop som sort of switch to tell ourselves "not this time" or "yes that time" but still in my opinion is playing with fire. Down th road your dick will think that a woman in front of you means staying limp for PE.
Now somebody with premature ejaculation can benefit from this because that same training would desensitize him psychologically and physically.