I am not too fond of having too many boards; I think that the level of compartmentalism that this site has is about right.
If there are a lot of topics started on the old west, then it might be useful. However, I don’t think that you can have a board for every possible war or period of interest. For instance, one of my ‘wouldn’t it be nice to have a go at’ periods is the War of 1812, but I am sure that there wouldn’t sufficient interest to justify a board for that. If I wanted to pick people’s brains on the War of 1812, I could either ask on the Napoleonic Board, or the General Horse and Musket Board.