In 2001 Andy Beal a Texas billionaire, challenged the local pros in Las Vegas to 50,000/100,000 head up poker. A syndicate of well known poker players put a bankroll together and went for it.
One of Andy Beal's tactics was to always time down 45 seconds before acting on his hand.
This game went on sporadically from 2001 for several years and even had a reboot after a long hiatus. The last match I can find is between Ivey and Beal in 2015, were Beal lost 16.5 million. If I recall Andy was pretty close to even a lot of the time and did not loose much overall. Even the sessions with Phil were not that dramatic as far as standard deviation goes, 160 Big blinds, that translates to being stuck in a 1/2 game to the tune of about 350.00.
A good book on the game, although published before the last game ended is "The Professor, the Banker, and the Suicide King: Inside the Richest Poker Game of All Time"
I think Andy's stopwatch tactic helped him. From what I understand Andy was a pretty good poker player and for him to do as well as he did was pretty fantastic, considering the lineup he was playing against. "The Corporation" consisted of players like Jonny Chan, Ted Forrest, Jennifer Harmon, Doyle Brunson, Todd Brunson, and other highly capable players. Andy played all alone but the corporation had an advantage of being able to switch out players (although they may have been limited to doing this to every couple hours).
As an aside, around 2006 I had a partner on my forum who was a blogger and poker dealer at Bellagio. Doyle got word that details of the big game were getting out online and insisted to powers that be, that it stop. My friend was told to stop under threat of termination. So the information was sent to me and I posted it at the forum for a year or so before they took another long break. The forum has been gone a long time, but you may be able to find it on Wayback.com, the domain was pokerclan.com. My site even got a citation in Michael Craig's Book "The Professor, the Banker, and the Suicide King: Inside the Richest Poker Game of All Time"
I mention the book and the website because there was conversation in both about Andy's use of the stopwatch. My friends blog was called PokerWorks.com, the domain is expired and I was unable to find archives. I did find this link to some of her stuff.
Linda blogged extensively about the big game and had many friendly conversations with Andy back in the day.