I have 2 at work. Sometimes I just have our ticket software on one and Firefox on another both full screen. When works crunching I might have multiple PDF manuals open on one and PDF schematics on another and could use a 3rd for a browser window to search for old similar problems in our daily reports. I’m able to work best when I can keep 1 screen dedicated to what I’m working on and the others for information gathering.
At home I typically just have 1 screen for gaming. I might set my laptop up on the desk if I want to browse the web or chat while playing.