It bothers me a little to call this trend ‘western’ because when I think of western, I think Cavender’s Boot City and Shepler’s. Part of that is because I live in Texas, I’m sure.
The ‘Western’ trend for this fall is more complex than that, encompassing quite a few different styles:

Country: denim, plaid shirts, big belt buckles
Native American: beads, feathers, Navajo style prints, turquoise
English Country: cropped pants, booties, riding boots, scarves, hats, capes

It also incorporates some pieces that are trends in their own right (booties, riding boots, plaid).
Mixing these different ‘western’ styles seems to be okay. It’s also okay to go completely ‘English Country’ or wear just one item without doing up the entire trend.