This is sort of a work-backward topic for me. First question is: do I have a legal obligation to someone? E.g, a publishing contract. If yes, then they get to have input in concept, completed draft, and final edits. There's a legal document that says who gets to have a say, in what, and what the consequence are for ignoring them. Easy answers there.
If I don't have a contract, but I have an agent, I am likely to seek their input on "what's next." Eg. I'm tossing around three concepts, which is the one they feel most able to sell? To me, an agent is there to help me plan my career short and long term as well as sell my manuscript(s) to publishers. Some people have agents who also provide editorial feedback in addition to career planning and mss sales. If edits are part of the established relationship, then value your agent's opinion or get a different agent.
If I have neither a contract nor an agent and all decisions are mine, then I default to my gut. I'm not a sharer of concepts or incomplete works. I'm the Critique Partner who will hand over a completed draft before I solicit feedback. In reverse, I'm the Critique Partner who is most effective when I have your completed draft. My editorial strengths are in the development of plot and character. If I don't know where your character is headed, I can't really tell you if an explosive action response is the best next step. I have had potential CPs who worked best exchanging chapters so they were receiving near-constant feedback. I wasn't the right fit for them. I didn't like them any less as people, we simply weren't compatible as CPs.
Beyond the CP stage, I trust the professional editors I've paid. I've had one crappy dev editor, and the rest have been amazing. I've learned that I need to tell my editors if I have specific questions or perceived story issues, so they know--that in addition to whatever they find--they need to also acknowledge whether my issues are legit or "just me."
That's my process. While I don't like brainstorming my concepts with other people, I love brainstorming other people's ideas. Yes, it's a double standard.
Dear Readers, if you're questing for sources of feedback, the first question you must ask yourself is "what do I want from the people with whom I'm sharing my ideas/work?" Be honest; otherwise, you're in for a boatload of butthurt on both sides. Some authors need adulation, encouragement, and positive feedback only. They're not emotionally prepared for someone to respond with constructive criticism. Similarly, the "constructive" part of criticism is a skill that requires practice. Tact and tone are hard to convey in "track changes." If you're open to critique, great, but everyone has different thresholds and tolerances for how much and how phrased. Communication is key to fine-tuning any relationship. It's okay to say, "Hey, this [specific example] is a little harsh for me. Next time, it'd be easier for me to hear the feedback couched like [specific example]."
So, the short bitchy answer to this week's question is: I trust people who've proven their value. Everything else is DNGAF.