Currently there are only 8 slots in the Key Command editor for Visibility Configurations. Although you can create as many configurations as you want, you can only assign 8 of them to key commands.
See: Key Commands >> Channel & Track Visibility >> Visibility Configuration 1 - 8
Would be nice to have quite a few more - perhaps 20 total? I can get around this by creating Project Logical Editor setups (using the naming feature), but it would be much easier just to setup a bunch of configs right in the timeline and just assign a KC.