[snipped taking a silly question seriously]
I don't know what routes you're measuring, but I'm seeing sticking to US 395 (except around Susanville) as shorter. The Goog gives the following for Phoenix to Spokane (all routes using future I-11 to Vegas):
*1285 mi via US 93 to Twin Falls, I-84 to Boise, and 55-US 95-US 195 to Spokane
*1338 mi via US 93 to Twin Falls, then Interstates (except US 395 in WA)
*1358 mi via 376/305 across butt-fucking Nevada, then US 95-US 195 to Spokane
*1386 mi via 376/305 across butt-fucking Nevada, then US 95-78 to Burns and US 395 to Pendleton
*1404 mi via US 95-US 195 from Vegas to Spokane
*1431 mi via all Interstates (I-15 to I-90)
*1498 mi via Reno and US 395 to Pendleton
*1511 mi via Reno and 139/39-US 97 to Biggs Junction
tldr: poo