Well, I did say “mostly”! 
It’s not possible to avoid the downtime entirely because the container has to be restarted during the update. But in my experience the downtime is never more than a minute or so.
I update daily myself but my sites are quite small and I am obsessive about seeing the latest changes. Nobody has ever complained to me about the downtime.
I am curious..why are you updating daily?
What does this mean?
That really surprises me! How much downtime did you have and for how long?
I am out of my depth talking about google. I don’t worry about it for my sites (they are small and private). Also, google is such a black box! It can be hard to know why things happen there.