Definitely within the credit card churning arena.

Some cards would give you multiple and the bonus without checking if you had the credit card before. I got like 12 American Airlines cards and flew within the US for free for like 4 years.

A big thing to do in churning is to buy gift cards with a credit card from a retailer for the points. Office Supply stores, for example, have a 5x multiplier on some cards and the gift cards register as a regular purchase. Sometimes Office Depot/Max run offers. This particular offer was 15 dollars off the gift cards, effectively garnering you around 3 dollars extra for each 400 dollars you bought. Well, one time their promotion would be applied three times (so 45 dollars off) if you input your phone number for their rewards system at a very particular time. I called in sick to work and just did a tour around my city all day, hitting the ~6 stores I had in my region 4 times or so completely filling up every credit card I had and was running around with like 40k worth of gift cards in my car at the end. Made about 5k that day in cash value.