- Unscheduled calls are if it's an emergency or something that you need an answer to right now
- Calling twice in a row is an emergency
- SMS if it's important but not urgent
- Discord chat if it's just casual messaging or pics
This is how my family and everyone else I know communicate, but my wife. My wife will call me repeatedly to tell me that they just got out of work and are going to the store. It really doesn't help that the bluetooth in their car is trash too, so answering the call is rewards you with feedback hell. It gets me in the habit of not dropping everything to answer their calls if it's around when they get out of work, which has bitten us twice when they couldn't get a hold of me for a bit when they had car trouble and needed a rescue.
To me, personal calls operate on a reputation system since you don't know what they will be about until you're already answering them. If you burn that rep on calls that don't matter, all someone will think the next time they see you on caller id is that it can wait.