The Launcher control panel supports a total of eight buttons, created by naming folders with a bullet (Option-8) as the first character. If there are aliases in the root level of the Launcher Items folder, then only seven new buttons can be created. The Application button is created by default for the 'loose' aliases. However, if there are only folders whose names start with a bullet, then eight custom buttons can be created.
There is a 40 item limit under each of the eight buttons. Additional items do not display, even if they are placed inside the Launcher Items folder in the System Folder.
This information is current as of October 1998 and version 2.7 (System 7.5) and version 3.1 (Mac OS 8.5) of the Launcher control panel.