It really depends on the person, but you're right. On average, we tend to find that most people have about seven colleagues that can provide really actionable feedback to individual contributors. Managers are larger, as they have a team, as well as cross-functional responsibilities. Executives and senior management it varies, but it's not uncommon for them to regularly interact with 20+ people.

That being said, as I state in my above post, NPS as a replacement for a 360s is a new concept to me. Bit of a head scratcher really.