WetGeek There can be a new layout in each desktop, instead of just one window.
One thing I like about Bismuth for KDE: just because it's installed and enabled, doesn't mean that it needs to be used. So far, I've thought of only one common situation in which it might be useful for me to tile two application windows in the same workspace. I sometimes use Dolphin and Konsole together. Having them in side-by-side virtual desktops is easy to work with, but having them side-by-side in the same desktop might be even more convenient. (Neigher one requires the full width of my HD screen to be useful.) I'm sure other uses will make themselves apparent from time to time.
My point is this. I can leave Bismuth installed and enabled in the system settings, but if I continue to use one application in each virtual desktop, as always, my workflow won't change at all. But if I have a situation where tiling two or more apps in the same desktop makes sense, I can easily do that simply by starting them both on the same desktop. So, it's an as-needed thing for me, without changing anything else after simply installing Bismuth, as I desribed above, and enabling it in the system settings.