"Blocking regime" behavior question

[Dhalgren Tor]

Ah, I see GoDaddy has something like eighty name servers and that any
one domain has NS records pointing to just two of them.  Depending on
how requests are grouped it could lead to several servers being
"blocked" and several others being left "unblocked" and more than a
few active requests on the queue.  Is that the explanation?  Or is
there more to it?