I recently made a similar question, sorry for that, but it has a little different variable.
1 SSD for the OS and apps and 1 Nvme for files, cache, renders and exports is the way to go but...
what if I had more SSDs available? Is it a good idea to spread files, cache, renders and/or exports to any other (slower) ssd (keeping something in the Nvme of course)?
I mean, will using more sata SSDs help the Nvme with tis workload?
I doubt it very much, unless you have huge projects. With 5 to 6 times the read and write rates putting any project files on the slower devices most likely would not improve the situation.