If it’s async, it’s not a standup, it’s something different, and far far better.
What do you call that? “A-sync-up”?
I haven't been in a position to proscribe process, I'm just a consumer. We have tried leaving messages in Slack but that process always ends in a matter of days from disinterest.
The lack of a detached floating window for huddles compared to Slack calls is a big regression in functionality for me.