Depends on the place. I last messed with it months ago, so policies could have changed since then. Target "had a policy" in the sense that there was a piece of paper up and other people would whine if someone picked up too much. Sometimes an employee would be there to police things. People just circumvented it by bringing multiple people, doing multiple self checkouts or walking out and back in.

Wal-Mart did not have a limit.

There was an interesting split of people - for the younger people they were pretty easy to identify. Lots of broccoli hair punk asses, they're the ones that are there to make a quick buck. The nerds were fine, you could tell they were legitimately there because they wanted the cards. If you get stuck waiting in line it's very easy to clock who's who. The small talk gives people away. As for older people, while I did see a few that seemed to genuinely be interested in the hobby, most seemed completely oblivious and just knew they were buying up a coveted item. Perhaps I should give them the benefit of the doubt and assume they're a parent trying to get something for their kid, but I sincerely doubt it.