I had each $50 no deposit christmas gift from Cherry Gold and Free Spins casino. It lasted me about 10 min at Cherry Gold because I didn't get any bonus round there and it lasted me about one hour at Free Spins casino.
I had 5 scatters in Tiger Treasure game, however, I didn't win much on its free spins (see screen shot). My balance went up to about $200, then I started to play Funky Monkey and it was a disaster. I played out the entire balance on Funky Monkey, but I did not get even one bonus round. It taught me a good lesson though, it doesn't matter how much money or how long I spend on the game, when it doesn't want to give me bonus round, I just won't get it.
I was expected to get to the bonus round on my next and next spin, but I didn't get it and my balance went down to zero, I still didn't get it.