What you can do here
A circle is a group you are actively working. Prospects you are building toward, people you are considering for membership, everyone you met in a particular month. You decide what holds the group together.
Inside one, you can see who to reach out to next, attach notes and meetings to the group rather than to one person at a time, and record how the work is going and what you have learned from it. The knowledge ends up tied to the group, which is usually where it belongs.
Signals
You can turn on news and company signals for a circle, so when someone in it or the company they work for is mentioned somewhere, you hear about it rather than finding out late.
Why group at all
Because a network is not one network. The people you are raising from, the people you are hiring, and the people you met at one conference are different projects with different rhythms, and treating them as one list is why most systems stop being used.