^^^^
You could carry it further than that. There were NO games that reached a fourth overtime from 1951 until the legendary Caps–Islanders Game 7 in 1987. None. Since then, including that Caps game, there have been eight games that went four or more overtimes (of a total 14 in league history). Statistically, you might expect there would be more simply because there are so many more playoff games each year than there were in the six-team era, but that hasn't been the case. There was the one 4OT game in the 1980s, two in the 1990s, two in the 2000s plus two 5OT games, and none since 2008 until yesterday's 5OT game. Incidentally, other than the Caps–Islanders 4OT game, no game in the 1980s even made it to 3OT.