ive said it before but ive been out of town for every single big event over 15 here. hit that number a few times though, feb 01, mar 01, jan 16, feb 17 all about 15"
Id try to see it from their prospective and take into account logistics and priority. The snow wasnt nearly as heavy so they could focus on side streets more.
When theres this much otg and this heavy for several hours straight, highways and main roads probably take priority. I'm no expert but thats just the logic i see. Happens almost every big storm. Lots of passes early then they're gone until the storm is over.
This is from 2018 and it looks like 1/4SM is fine and yea 4 hourly obs would be a 3 hour window so that makes sense.
https://www.weather.gov/okx/Blizzard_Jan42018