I've been collecting silver coins from circulation since 1982.
Half of my silver Quarters are 1964-D's, in every grade from VG to BU.
Most are in VF-AU grades, they were pulled from circulation rather
quickly, and dribbled back out in decades since (getting little if
any wear, before someone like me would pull them from circulation).
One day in the early 1990's, I got four '64-D Quarters in one day!

About 9 out of 10 of my 1963 and earlier Quarters are also D's.
With my hoard so heavily "D" biased, I tend to think some of these
coins have never actually left the city that minted them.
(particularly the higher grade 1964-D's).
Earlier this year at a Denver coin show, there was an unopened
original (Denver) bank box of BU 1964-D Quarters at one table.
That same seller was also selling BU rolls of '64-D's.
I don't know if he managed to sell that whole box intact....