romsort

Utilities to help you sort bunches of files (limitation of USB stick or SD card, for Mini, is 256 files per folder).
Both have their own, specific (dis)advantages. Generally speaking, RomSort is more oriented to folders, Folder Axe to files. In most cases, none of them will provide one-step solution for your needs. Folder Axe has “copy” (instead “move”) and “undo” options, which is a big plus. However, it is not developed or supported for many years.

RomSort

RomSort - a small utility to sort a directory of files into alphabetical sub-directories. It could intelligently combine the smaller sub-directories.

https://jonthysell.com/software/romsort/
https://github.com/jonthysell/RomSort/releases/download/v1.0.0.0/RomSort.1.0.zip
Windows only (.NET 2.0 required), but should run on any system that supports .NET 2.0 (WinXP+, Mono).

Folder Axe

Folder Axe splits folders into many smaller folders in various ways.

http://www.tucows.com/preview/1201317/Folder-Axe
https://web.archive.org/web/20180328045037/http://bkprograms.weebly.com:80/folder-axe.html
Windows only (.NET 4.0 required), but should run on any system that supports .NET 4.0. It works flawlessly at Linux (via WINE).

Suggested by Mike Burgess in fb group post:

https://www.facebook.com/groups/209280506324242/permalink/353812808537677/
“I used Romsort to sort my files alphabetically; if a file had more than 256 files I used Folder Axe to create subfolders” (at comments)