Again, from what I understand, this would be active surveillance targeting an individual and the bulk data would not be collected (even if technically feasible

Again, from what I understand, this would be active surveillance targeting an individual and the bulk data would not be collected (even if technically feasible given the mechanism for collecting the individual's data). From write-ups of the 2013 leaks, we saw references to violations of the legal theory used to justify the Presidential Surveillance Program. One of those violations was them unintentionally collecting the wrong data, due to how the ISP was bundling packets or something like that, which constituted a warrantless search, and they supposedly took that very seriously because it jeopardized the whole program. My take on the surveillance program is that they try very hard to be law abiding, even if they have to stretch what the law means to justify the program. If you are worried they have a warrant for your communication, a VPN isn't going to help you. If they don't have a warrant, they will avoid U.S. citizen's content like the plague for fear of compromising the whole program.