I have a three 27" monitor setup with iMac. I tend to dedicate one display to communication and entertainment apps--Outlook, Slack/Mattermost, Spotify; I'll have my IDE in my center display, and on the third display I'll have terminals, utility editor windows, or browser windows--depending on what I'm working on, e.g. when writing front-end Javascript, I have my browser and developer tools open, and maybe a window open to MDN's docs.