Can anyone help me understand this option?
Firstly, it seems redundant. To get it to work, you have to put a varying placeholder in the export filename, and there's no other point putting in such a placeholder, so what's the point in having the checkbox option?
Secondly, it seems that it is mis-named - it does not make the number of files per directory one. The number depends on the placeholder(s) in the filename, and can be zero or more than one.
Please do correct me, experts!