There are a couple of lines of thought for projector distance.
The closer the projector to the screen the brighter the image since you will have to zoom the image out farther. The farther the projector from the screen the more dim the image. OTOH the farther the projector the better contrast and image clarity you will get especially at the edges of the screen. IMO though you won’t likely notice the better image clarity unless you are using your system as a computer monitor like I do.
The projector central calculator is only and estimate of how to place your projector as Randy said your best bet is to experiment with location. However, be careful not to move your projector around while the bulb is hot, there is probably a warning about this in your manual.
I ended up putting my projector at 19 feet which is way out of the optimal range for the Projector Central Calculator because my room is completely black so I don’t need as much brightness and improved contrast and image clarity for reading computer text is more important to me. Also it keeps the projector as far away as possible allowing me to use high altitude mode so the fan runs faster and keeps the bulb cooler but I still can’t hear it because of the distance.
Also as Randy stated there is the zoom factor in dealing with different image ratios that may also be effected if you put the projector at the extreme ends of it zoom range.
