It does happen, and it's not as rare as you seem to think. Pitt 'should' have a policy in place decided by the BoT for how undesignated bequests are distributed. This is especially true when a University is in a campaign. That policy may or may not state that money from those types of bequests get placed into the endowment (or a portion to endowment and a portion elsewhere). However, this is Pitt we are talking about, so they may very well do it willy nilly.