There's little need for multiple monitors if you can switch virtual desktops very easily and quickly. The best method I've found is using a switcher control in the corner of the screen that can be operated by the mouse wheel.

The corners of the screen are the easiest targets to hit because they have effectively infinite size (see Fitts's Law). The mouse wheel is the best input to use because the mouse wheel is always non-destructive in standard desktop GUI software (equivalent to HTTP GET, not HTTP PUT). So long as your switcher control does not wrap around, you can set your two most important desktops as the first and last desktops, and access them with no conscious thought by jerking your arm and blindly scrolling the mouse wheel.

I use a patched version of lxqt-panel for this. The official version wraps around while switching desktops with the mouse wheel. This is IMO a bad idea because you always have the option of clicking the numbers directly, so it doesn't save any time. I have all animations disabled (essential for this system to be tolerable). I use three virtual desktops, with the the middle one reserved for less important tasks. The middle one requires conscious thought to access because I have to scroll the mouse wheel more carefully. But when accessing the main two I scroll the mouse wheel fast enough that I don't notice it.

Theoretically it would be possible to have unconscious access to 8 desktops this way (mouse wheel up and mouse wheel down for all 4 corners) but I haven't implemented this because I'm happy with two.