As far as I know, this just amounts to a change in the partition table and it is a relatively safe operation that is rather cheap.
Is there any significant cost or drawback(s) to...
- Creating and destroying partitions all the time
- Having lots of partitions, mounting them, and actually using them to write and read lots of data and expecting this to perform at the same level as if we were dealing with directories in a larger partition
For the latter, I can think of several factors that could affect this in theory, but all of them should be negligible in practice.
Just general curiosity, this is not something with a real use case