It depends on the dog. I could never do this. Freyja would eat until she was too fat to walk, she would them figure out how to roll to her dish and eat more. My parents collie on the other hand is free fed mainly because he is such a slow eater. It seems like more dogs would gorge themselves if given the chance.
Freyja GSD- 6/21/10
Bevin (princess kitty) 08/27/07
Porsche: kitty 7/2012
Teddy (collie)- 1990-09/13/2006
Franklin (collie) 1996-06/26/2006