I don't know if this has happened to you much, but I usually play slots from time to time and when I get free spins I usually win something, sometimes more, sometimes less, but I always win. Today I got two rounds of 10 free spins playing Wild Bounty Showdown, and in the first one I didn't win anything, while in the second one I won about $0.34 (playing $0.20 spins). I felt a bit silly, because getting free spins is cool, it's usually exciting, and I've won some good big wins a few times.
Has anything similar happened to you?
Most free spins rearly gives big wins, you find out that it is only 1% out of 100% gamblers bing offered free spin that will win something reasonable compare to when you place a bet.
The free spins are just a bonus to compensate gamblers and strategy to retain their customers, so that they don't feel financial overstressed, and it depends on the level of your patronage that will determine your free spins, except it's general to all customers.