Tom was an exception to the rule. Vito loved him as a son, and Michael respected Vito too much to get rid of Tom completely. Michael demoted Tom while Vito was alive from consigliere to "our lawyer in Vegas" on the grounds that he was not a wartime consigliere. Tom kind of wormed his way back in after Vito died, and especially after the hit in Tahoe. While he wasn't made, he came pretty close in the Geary blackmail. He had a direct hand in the murder of the prositute, and even had to give Neri a dirty look to keep the whole thing a secret.

He was also directly involved into sending Tessio on his last car ride and talking Frankie into suicide , so thats probably close enough.

I don't know about real life consiglieres, and leave that one to people who know more about the mob than I.