Athlon Preseason Top 25 - Street & Smith's notes that the Big Sky scheduling "gives certain teams an advantage because of the unwieldy 13-team conference."
"This year it's Eastern Washington, which avoids playing both Weber State and UC Davis as well as the fourth Big Sky team in the playoffs in 2018, Montana State."
Parenthetically, similar things happen in the Big (14) Ten where teams play the other six teams in their division but only three teams in the other division. (It used to be just two...) As a result you can play in the Western division and while you play Nebraska, Wisconsin, Iowa and Northwestern, anyone of which may be having a good year, you might avoid Eastern division teams like Michigan, Michigan State, An Ohio State University and Penn State and only play Maryland, Rutgers and Indiana.
Of course the athletic directors like getting a piece of the gate receipts when you play at Michigan, An Ohio State, or Penn State. Indiana, not so much.