I like having separate forums for San Jacinto and Other Areas.
This site is unique in its coverage of the San Jacinto Mountains.
The San Gabriel Mountains Web site does a good job of covering that area. There are enough posts here to argue for keeping that coverage here. However, this site is not the main one covering the San Gabriels.
The SGW site is active and popular but it is not particularly useful as an archive. Again, this site gets enough posts on the San Bernardino Mountains to argue for keeping that coverage here. On thie other hand, it is not the main, or at least not the only, site for that area.
So, I would keep one forum here for the San Jacintos and one for "other."
I agree that people often post in the wrong forum. Perhaps some reminders would help. Also, posts could be moved to the more appropriate section.