I'm pretty sure a 7AM Monday intra-CA flight would be where you'd see that and I have NEVER seen anything approaching it.
Close - SJC to SAN, Thursday afternoon, Feb 17 - flight 243, 5:40 pm. I am A-list, checked in T-23:55, booked the ticket on Dec 11, received B20. Without being too intrusive, I scanned boarding cards of those in the A group, all appeared to be A+.
As it is a popular flight, WN uses Evolve -800, so the sardine can is packed to the gills.
Gate Agent claimed that less than 40 people checked bags, was attempting to encourage people in high B, C to do so in advance, as there would not be overhead space.
While some claim to have never seen it, this is the reality at least some of us live.