They claimed several prevented attacks but refused to provide details.
And given the way they publicise the "attacks" that they "stop" which are really just an informant giving fake bombs/weapons to some nut job ... you know they'd be shouting any successes from every rooftop they could get to. They'd be doing the talk show circuit and hosting their own news conferences.
The first problem is that the kind of "terrorism" that they want to focus on is almost non-existant in the USofA. The real terrorists had one huge success and that's all.
The second problem is that the real terrorists don't spend time gossipping on the phone with all their terrorist friends. Yes, it is a way to map out a social network. But this isn't Facebook. Sam the suicide does not have to call Bill the bomb every Tuesday at 7 to chat.
The metadata and phone location are useful for reconstructing the final days and those contacts AFTER an attack. And they don't need years of data for that. Or even months.