The NCAA allows leagues to choose whether, after a mandatory five minute OT, they want to play an additional five minutes of 3x3 with a shootout, or just have a shootout, to decide regular season league games.
The three western leagues, plus Atlantic Hockey, use the 3x3 plus shootout. Hockey East and ECAC simply end games after the five minute OT, as do all non-conference games not part of tournaments.
For tournaments mandating advancement, there is an option to use either shootout protocol, or to use a series of twenty minute OTs as they do in all postseason games. They must choose whether it’s five or twenty at the outset, and can’t switch to the other.
That being said, the NCAA doesn’t regard any overtime result after 65 minutes as anything but a tie when it comes to its record keeping. For RPI and pairwise calculations, ties are half a win and half a loss (so a team that’s 20-10-0 has the same winning percentage as a team that’s 19-9-2 or 18-8-4).
