That's not what we're discussing here, you can't just say "I plead the fifth" and walk away if the people in charge decided you wouldn't walk away, no matter what's right or "legal"

Francis Rawls stayed 4 years in jail despite pleading the fifth all day long

That case also established 18 months as an upper limit. If you are in that situation it is usually better to simply jot divulge. Especially if there is incriminating evidence. Or you are a journalist being harassed by the DOJ. It can only bring you more pain. They will always find something.