I'm of the thought that "a good dog prevention makes", especially during formative years. The more "mistakes" they are able to make, the more conditioned they become to the behavior and the harder it is to help them come to a "new" understanding regarding things in general. I'm more comfortable guiding them on that road until they "get" it.
I'm also of the thought that I don't want to leave my dog crated all day long while I'm at work, so I attached an xpen to a crate and kept Chili in there while I was gone until she was almost 2, with shorter periods of house privileges while I ran to the store, etc. - trial runs, if you will. She never touches a thing that isn't hers. Right now, she's earned two rooms - the kitchen and the dining room - while I'm gone. She's got a nice little setup and is quite happy with it. I now have the xpen opened up across the windows to the yard in the dining room, so just in case she should decide "that squirrel needs some chasing"
she won't put her paw or nose through the glass to try and accomplish the task! She could have whole house privileges right now as far as "stuff" goes, but I think she and Bamboo kitty are having too much fun with each other when I'm gone, so they BOTH need to grow up a bit more before I'm comfortable with the wrestling while I'm not there to observe (the kitty is the biggest instigator
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