Depends on how far you are sitting away from your monitor. There are calculations online that can tell you the maximum size of a monitor @ dpi depth that works at each foot of distance from the monitor. My compromise is to get the maximum size monitor at the maximum dpi so that I don't have to rotate my head and then adjust my workflow to fit on a single large monitor. I have a tiling window manager so this setup can be effective. The largest size monitor on a desk that I can see my self getting is an 8k tv @ about 64" in size. It occupies the whole back of the desk, has the max resolution that the human eye can see at the distance of a desk monitor. I'm waiting to see how 8k tvs turn out for people, not a lot of video cards can drive them properly.