I am new to mergerfs and have made a pool with the LFS (least-free-space) policy.
My reasoning behind it was that it made sense to keep as much of a specific kind of data on the same disk; for instance all the episodes of a tv series.
It also makes it easier to find files when a directory/file tree is not equally distributed among all the drives of the pool.
Also, using most-free-space (or an afterwards balanced mergerfs pool) would create a situation where it is unlikely for a disk to spin down, because it would more frequently be asked for data.
So my question: why would you balance the data among all the drives? What is the advantage?