Eighteen minutes missing forever

On Nov. 21, 1973, J. Fred Buzhardt testified and made the first relevation that 18 minutes of taped conversation between Richard Nixon and H.R. Haldeman was found to be missing. Rose Mary Woods testified she erased five minutes of tape by accident, but no explanation was ever found for the rest of the missing discussion.
It's one of the big mysteries of the Watergate scandal, but what could those 18 minutes add? The speculation all through the years has been pointing more of a finger at Nixon's role.
Ironically, the existence of the taping system was originally revealed by Senate Counsel Fred Thompson, who was questioning White House Aide Alexander Butterfield. Yes, that Fred Thompson. The Republican running (some say walking) for president.
Apparently the National Archives is still making an effort to reveal the 18 minutes. Would it do any good?
Hardly. Nixon's role in Watergate is well known. There really isn't much more trouble he could have gotten into than he already did.