I saw that in a D-3 game a few weeks ago. I didn't realize that it was an NCAA thing at the time, and wondered if I'd missed a couple of penalties just before OT...
All that aside, it's a fun format. SOMEBODY is going to win that MF, as opposed to boring "playing not to lose" OT hockey for (sometimes) hours on end.
With only 5 minutes to burn, you can play your 3 best guys throughout. If they need to get a blow and re-group, no change necessary, there's so much open ice to use to withdraw into the neutral zone, or even back into your own zone, and then to attack again. None of the defenders dare chase when there's so much space to pass the puck.
The BIG thing is to win the initial faceoff, cuz if you don't gain possession of the puck then, you might never touch it again.
(Blast from the past: I once (around the turn of the century) saw a Maine 3x3 for maybe 1:54 at UMass, and two of the three guys out there for Maine were your favorite Dipsy-Doodle guys, Keenan Hopson and the other guy. Both had good puck skills, and scored on that one. I don't remember the other guy, but he had hands. Help me out here. I want to say Thompson, but that doesn't sound right.)