> That is to say, stuff that's sensitive OPSEC stuff can often be declassified in a matter of hours or weeks... because the actions described by the classified information have taken place and everyone knows that they took place.

Minor quibble - this isn't always true.

If a hacker knows two vulnerabilities to exploit, but only exploits one of them, he keeps an advantage by keeping the extent of his intelligence a secret. If he only knows of the one that was exploited, he's not benefitted by admitting a lack of intelligence.

Apply to enemy troop positions and competitor pricing strategies as appropriate.