This is interesting! Thanks everyone who answered! I recommend checking the comments to see how different people use windows and tabs together.
I use one laptop and one external monitor above it. I usually keep a single browser window maximized on the external monitor, and use the laptop for video calls. But I also "lose" windows all the time, or have to open them separately for some reason.
So, I'm 3-5. 2 on purpose, and 2-3 because things don't always happen according to plan.