Idk about dual being bad, I don't know if it's the best though, but at least for me dual advice usually feels like someone confirming the things in the back of my head, like I am hearing solutions that I feel vaguely familiar with but now they are stated clearly, and that's what makes it click("I always knew that but it makes more sense hearing someone say it out loud"). I guess because those thoughts formed in the back of my mind I might not feel so sure or confident about, not knowing if they are the right answer, but hearing someone speak confidently about them and back them up makes me think I'm on the right track and gets rid of alot of anxiety and insecurity about them.
But yea if they do the work for you then it won't help you get better at it for sure. It just feels like they are telling you something you secretly already know, which for me feels pretty validating.

Idk, everytime I hear conflictor advice I immediately get exhausted, I will admit conflictor presence can make you a little better without you knowing it, but their advice, nah, it has never worked ime. I can't tell you how many Se filled motivational videos I watched on the internet and just feel completely defeated after watching them instead of motivated "HARD WORK! WORK HARD! PUSH YOURSELF!" as I feel 1D Se cringing in the background, and I don't feel the desire to be that way even though I can be envious of people who are like that, while with Te advice even when overwhelming I still think I need to be that way more while feeling it'll never happen.

But of course the best would be an identical whose already solved your problem, and their solution might make you face palm and say "DUH!".