My policy for calls from unknown numbers:

1 call: very likely spam; let it go to voicemail.

2 calls: Someone genuine is trying to reach me; let it go to voicemail. Listen to voicemail as soon as it arrives.

3 calls: emergency, pick up right away.

Exception: PagerDuty calls; pick up on first ring.

My wife is aware of this policy of mine. And I store kids’ school numbers in contacts.