You went to a really bad strip club from the sounds of it. At most clubs, the strippers charge per song. The songs always start RIGHT after the other one. There would never be a time when "each song was done", since they want to keep the girls dancing as much as possible. The songs are also very short versions of themselves, with solos and what not cut out to maintain the high energy. Due to this, it's super easy to get "scammed" by getting lap dances and forgetting how many songs you've been getting grinded on for. It's entirely possible that the girl just said he got 6 songs worth of dancing when in reality it's only been 2 or 3. Strippers always think they can pull fast ones on customers but it's important to remember that they're usually incredibly stupid and there attempts to scam are usually painfully obvious, haha.
That being said, I've heard of A LOT of clubs (especially in Montreal) where you go in and there are no girls dancing and the "bouncers" just beat you up and take your money. I'm not even joking.