Definitely used to/prefer seeing the cardinal direction to the right of the shield, although that may be the result of my preferred verbiage ("405 south", "I-90 east").
There are exceptions in WA; sometimes the cardinal direction is to the left of the shield, although 95% of signs have it either above the shield, or to the right. Another exception is when there's a split: there will be a line above/below the shield, with cardinal directions on both sides of the shield (
example).
One other oddity will be pull-through signage. In the past,
signs like these were used where there would be a single cardinal direction directly above the control city, with the shields off to the right and left edges of the sign (not anywhere near the cardinal direction). I think these are common in Minnesota too; I kind of like them, but they're pretty rare now, although that one (from the prior link) dates to 2008 and may have been the most recent install, and I cannot readily think of another example (I-5 northbound nearby at WA-167 had one, but it was removed).