I am assuming you are still putting the OS, projects and samples on separate drives, as not doing that will likely lead to some hiccups, and unworkable if there is too much going on.
With SSDs, because they do not have heads like HDDs, which need time to travel across a disc platter, there are no time penalties as to where data is on the drive, so partitions for speed optimisation are unnecessary.
With HDDs, if you want to minimise head travel time, and thus enable lower latencies, you are better off getting a larger drive, but creating a partition just large enough (with extra) to handle the critical data. Larger drives will have more heads, so there will be less head movement for a given amount of data.
However, if you do partition a HDD, do NOT use partitions on the same drive for the same purpose, as that will force longer head travel, and lead to larger latencies. That is, use the first partition for samples, but other(s) for anything but samples or projects, but instead for general data, backups of projects, or whatever.
I have two OS drives, booting from one for general usage, and the other for the DAW. I installed the OS on each while it was the only drive in the computer, so I do not use the boot menu, as I had issues of corrupted boot menus when I had to re-install an OS. The advantage of separate OS drives is that your computer is still usable if one OS drive goes AWOL.
I have all my SSDs in a 5.25" 6-drive bay, so when I want to boot to the other OS, I power down, open the current OS drive bay door, then restart the computer, which will boot from the other, and if needed, I close the other drive door. This is only necessary when changing boots, as the computer always boots from the last booted drive, unless it is offline, so it then looks for others.
I set both boots to use a common general data drive by setting each OS to use the same folders on it for Documents, Music, Pictures, Videos, Favourites and desktops.