I like having my display as bright as possible without it being uncomfortable; it helps with readability. On my laptop and phone I'll shift the brightness throughout the day to meet this heuristic, but alas, Windows does not make this trivial with an external monitor. Usually you have to fiddle with the monitor's physical buttons and navigate down into a menu. So I just don't bother.
Most desktop monitors have their brightness & other config exposed via the DDC (DDC?) protocol. This is a simple UI that exposes the brightness controls on Windows. Much easier than using the buttons.
You might need to go to the monitor's menu and enable DDC if it's disabled by default.
Windows has a brightness slider in the side bar, but it doesn't seem to work with external monitors. Probably because OS-level brightness controls were implemented when laptops became popular, and traditional PCs with external monitors became an afterthought.
Just realize when you use them as a justification for changing defaults which work fine for most everyone else, you're going to annoy people. Especially when your preferences tend to fly in the face of common sense.
