In the Google Legal building, the department that dealt with acquisitions was behind a locked door. Most badges did not open it.
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That's not a very efficient way to stop information leaks. It's not like ones and zeroes are delivered through open doors..
It will work against Big Bad Wolves, especially if your house is made of bricks.
Not doing that would be Security Malpractice.
But yes all these steps should be necessary to minimize risks.