Importance of steam during oven rise

Today, I had the most success ever with my oven rise. This is a loaf based on Norwich Sourdough (which is based on Vermont Sourdough), and I added some flax seed on top. I think at least part of my success had to do with my steaming. I used a cast iron skillet and made significant steam for the first 12 minutes of baking (1st- 1 cup of water in skillet, 4 minutes- 1/2 cup water splashed on side of oven, 8 minutes- 1/2 cup water again, 12 minutes- removed skillet and let steam out). This loaf came out with a delicious chewy & crispy crust, and a light & open crumb. I have used Leader's method of ice cubes & skillet at beginning of baking, but never have I such good oven burst. Anybody have any thoughts? Thanks!