There is no reason to keep SAC/SAW separate from the OS drive.

OS + Applications - C Drive
Audio/video project files on separate drive - D/E/F, RAID, whatever you have setup to store data on

So on my modern motherboard builds OS+Applications are on the m.2 Flash storage on the motherboard. A 2nd drive can be used as a backup for the OS drive in case of failure.

All data projects are on other drives (generally SSDs, but cost/TB is still cheaper to go rotational and video projects eat up a lot of space)

My newest pc (upgrade, I suppose you could call it) for the studio is equipped with a motherboard mounted 1TB, M2 NVMe Gen 3x4 SSD for the C-drive. It's the first NVMe I've used. So, I now have an assortment of NVMe, SATA SSD and SATA HDDs to distribute chores between.

Is there some consensus here, today, about how drives should be used for recording, editing, mixing and storing multi-track audio (and video, when needed)?

I've always installed SAW/SAC on a physical D-Drive, separate from the C-Drive and os.
Since using SSDs, I've installed the os and the bulk of programs (other than SAW/SAC and a handful of exe utilities) on the SSD and installed SAW/SAC on one of two internal SATA HDDs, along with current and ongoing sessions, plus a year or two's copies of recent sessions (Storing backups of all projects on external HDDs as well).

What's a good strategy, if I commit to this "new" pc) for installing SAW/SAC, other programs, projects (current and temp. backups) and sample libraries?