I know. As I said, there should be some sort of restriction on what exactly you can do given more time. And part of that would be making it so you can't figure out alien scripts or phrase codes without a reference, just like for completely unrelated languages.
My comments on taking 20 were only a comparison of the time increase DC modifiers versus the time increase for taking 20. And my conclusion was that they're irreconcilable, so I settled for saying you just can't take 20. What you can (or could) do with that 20, is an entirely different problem.
And are you sure about that time? DC 80... you need to reduce it by 70 to take 10... that's 35 doublings, or 2^35 minutes = 65,000+ years.
Half that if you take notes as you go.
Edit: Brain not work good. Too much read-read, learn stuff for test. Me sorry.
70/5 = 14, not 70/2 = 35. But 2^14 minutes is over 11 days.