I also have several separate drives with various libraries and data like Omnisphere and Kontakt. I don’t do partitioning anymore because it doesn’t make sense anymore nowadays. Making directories is a good enough separation for me.
Because of the speed of modern M.2 drives it doesn’t matter to put some libraries or sample content on you system drive. However, I choose to put the majority on separate drives but keep ten type of data separate. I basically have three types of directories on these separate drives. 1) Kontakt libaries. 2) Audio samples. 3) Program data (Spectrasonics steam folder, Sampletank sound data, BFD samples, etc) That way you always have a clear view of what kind af data is in what type of directory. Besides that I always try to put the most demanding libraries (mostly very large Kontakt libraries) on SSD because loading times are usually longer than other libraries. I put normal samplepacks with wav/Aiff files on normal conventional drives because they are less demanding with loading/reading but it’s advisable to use 7200rpm drives.
Once you have your Kontakt libraries set up I can really recommend you to do a batch re-save. This will will dramatically reduce the loading times of especially heavy libraries.