I think many people overrate Adriana's street smarts and intelligence in regards to the mob. She wasn't exactly a mob wife of 15 and something years like Carmela or Rosalie to know what's what. Besides, why would she know anything about how much coke would get her in jail for? I don't imagine Christopher, or any of the mobsters she was around ever talking about such things with her.

I don't think that Adriana would be savvy enough to immediately think of contacting Chris's lawyer, seeing as that would fit the aforementioned experienced mob wife, and Christopher was hardly more than a two-bit hood even when he got his button.

Also, most people are not very keen on spending time in prison, no matter how little it may be. Being with a mobster doesn't prepare you for that.