My opinion
I have done exactly what you are asking about. Because of my financial situation, I am disabled, due to work injury. My disability check pays my rent and food. I did not want to deposit, so I started freerolling on 2 sites, I'm from the US. Bet-on-line, and ACR. you need patience because freerolls are time consuming without much $ return. Anyway, because I had time, I have played for 3 months on BOL without a deposit. I play SnG's, some cash, and some MTT's. I did the same on ACR, and I am taking shots, in less than 30 days, I went from $0 (no deposit) to today Bal. $76.50. Again, I have all day so I play small stakes, $3-5 SnG's, 1/2cent cash. I want to experiment with MTT's because if you bink 1 you can increase BR by 500%