Apparently the PDB is actually a document, so it is something the president is supposed to read rather than attend. It's not clear how it could be known precisely how many of them Obama read.
Do you really think affirmative-action Clown Prince nobama can read?
‘Apparently the PDB is actually a document’
No, it’s an actual briefing. He’s supposed to listen to it, ask questions, and direct the briefers to get him more info on areas he deems a threat/important. Obama skips the briefings [most of the time] but claims he reads the report. There is no evidence that he does. If he had, he wouldn’t be blathering about how everyone was blindsided by ISIS. *He* is the one who was blindsided, because he skipped his briefings.
Briefings usually consist of two parts. An oral presentation highlights the key elements. The document provides more detailed information and background. One important aspect of any briefing is that the person getting briefed has the opportunity to ask questions of the person doing the presentation.
By skipping any in-person, oral briefing, Obama ensures that nobody can ever testify that he was TOLD about any particular threat. It creates instant plausible deniability for Obama.