Well, using sub-folder inside the Presets/Samples/Wavetables-folder helps keeping things organised but you don’t have to install them. I often use sub-folders for preset categories, e.g. Soundscapes, Drones, Pads, Leads, Sequencer, Percussion and whatnot. In the samples-folder I also install sub-folders depending on the size of the sample content, e.g. it makes sense to collect samples for large multi-sampled instruments inside a dedicated folder in case the user wants to build his own instruments using these samples.