You need one person's pick. You CC six others so nobody feels left out. The thread becomes a place people perform alignment. The person who can actually decide waits to see what the room says. A week later you have three "looks good"s from people who were never going to own the outcome, and silence from the one who was.
A wide CC is not inclusion. It is an attention tax with a social excuse.
An ask needs one owner
A decision request names who takes the outcome. A CC list blurs that name. Everyone can see the question. Nobody is sure it is theirs. The reply mirrors the request: a crowd produces crowd-shaped mail — hedges, plus-ones, and a joke.
Respect the reader's time includes the people who cannot help. Every extra name is someone who has to open the thing, decide they are not the audience, and close it. That is not free. It is how a team learns to ignore you.
The audience changes the writing
When you write to a room, you write for the room. You soften the ask. You add context the decision-maker already has, for the benefit of people who should not be in the brief. You leave in a nickname or an aside because the inner circle "already knows." Then the outer circle reads it.
A briefing to one person can be shorter and more honest. After they pick, you can send an FYI — no ask, no performance — to the people who only needed the outcome.
Cross-company CC is a different mistake
People at another firm should not live in your team's thread. They will not join your Slack to be CC'd there either. Write them a package. They may have no AI. They get email and a page. They do not need your six colleagues watching.
If two companies must both agree, that is two asks, or one ask that says you need both picks. It is not a twelve-person CC that nobody can answer without a meeting.
When a second name belongs
A counsel who must see the words. An owner you are informing as you ask someone else. A person who will execute the pick. Those are named roles, not a blast. If you cannot say in a clause why they are on the send, they are not on the send.
RelayLink correspondence is already one-to-one in spirit: a package, a recipient, a reply. That is a feature when you are tempted to "keep the team in the loop" as a substitute for knowing who decides.
Send the ask to the person who can close it. Tell the others afterward. The loop is shorter, and the people you did not tax will still be willing to open the next one.