How Do Google Algorithmic Slow Rollout Work?

Google often says that is algorithmic updates, be it core updates, page experience updates, and other search related updates can take several days to several weeks or even several months to fully roll out. What does that mean, how does that work? I was asked on Twitter by an SEO named Jabroni Slayer "How exactly (technical explanation) do they roll it out several weeks?"

from Search Engine Roundtable https://ift.tt/3gJKQfT