Best HD formatting for LR 13.5.1 and Mac OS Sierra

Howard Oakley wrote an excellent article about this:

Should you continue using HFS+?

From his tests, apparently on hard drives APFS performance is OK if the data isn’t going to change much, but as working storage where the data frequently gets changed, the hard drive could eventually slow down from severe fragmentation.

Translated to Lightroom Classic, that might mean:

If you use the APFS hard drive as long-term storage for originals, so you put photo files on it and they rarely change or move after that (because Lightroom Classic write edits into the catalog, not into original files), performance might be OK.

If you put the Lightrooom Classic catalog folder on the APFS hard drive, in the normal course of using Lightroom Classic, as the catalog file changes every time you use Lightroom Classic, and the previews are constantly generated, regenerated, and deleted, maybe that constant re-writing of files would over-fragment the hard drive and it might slow down. If you wanted to use the hard drive this way, maybe HFS+ would be better.