Why should anyone have to think about number of items at all? For most of computing history, the only thing people really care about is storage space, not items stored...
FAT16 has a limit of 65460 total files. FAT32 limits 65535 files in a directory.
The RISC OS ADFS filesystem had a limit of 77 files in a directory; I used this until about 1994.
There are also limits to number of files in a directory.