iCloud nags appear in the Settings app and Notifications menu. When you are signed out, Apple will assault you with notifications (that you must disabled with a script) until you log in: https://discussions.apple.com/thread/250786208?sortBy=rank
I've got my fair share of horror-stories with both OSes, I switched between dailying Mojave and Windows 10 for a big portion of my life. Nothing will ever top updating to Catalina, booting up Ableton Live and seeing all my paid plugins go from "working fine" to "completely unsupported" in the span of an update.
I see. I think part of the reason why I don't see this (or don't remember it?) is I treat my work computer differently than my home computer. For my work computer, I honestly only restart my Mac maybe once every few months and never install updates. By the time I'm 1-2 OS releases out (usually when the battery starts to fail), my company gives me the latest macbook.
For the people in the office who use Windows they start dropping off randomly during the day as their computer decides to start installing updates during critical times.
I've got my fair share of horror-stories with both OSes, I switched between dailying Mojave and Windows 10 for a big portion of my life. Nothing will ever top updating to Catalina, booting up Ableton Live and seeing all my paid plugins go from "working fine" to "completely unsupported" in the span of an update.