Maybe I'm forgetting something, but I don't really know how anyone has any idea how long she spent at MB/CR's or JR's.
There has been isolated (unsourced) accounts that have given time estimates of staying at CR/MB's for an hour and another that says arrived at JR's at 3:15. Obviously conflicting and I don't put any faith in either one.
Here is one:"Spierer and Rossman left the apartment building and she escorted Rossman back to his apartment. She was there for about an hour with Rossman and another young man.".
And the other: Spierer walked Rossman back to his apartment, two doors down from Rosenbaum’s, before going to Rosenbaum’s apartment at approximately 3:15 a.m.