The Mueller investigation has been going on for a year. That may seem like a long time, but this handy chart from TPM puts it in perspective.
(And I don’t remember any Republicans calling for Ken Starr to “wrap it up.” As far as they’re concerned, it’s still going on; they just know there’s still some dirt to be had on Bill and Hillary and that airstrip in Arkansas.)
What I think is telling is that the learning curve on these types of investigations is so obvious. In every case illustrated above, the perps thought they could get away with whatever it was that they were doing and that this time for sure they’d bamboozle both the investigators and the public. It never works, and someone — usually a mid-level minion — ends up in jail. (Interesting to note that in all of the investigations, at some point someone involved in the case was able to wangle their way into a presidential pardon.)
So take your time, Mr. Mueller. Compared to Whitewater, you’ve got another seven years ahead of you.