Don't know. Don't have the time to run it right now. Would imagine shot attempts are used because like you said, more data to work with.
It's not that simple tho.
If you tell your players to 'outshoot the other team' they'll be launching shots that aren't quality. You need quantity, quality, suppression, every little thing that leads to an attempt for or an attempt against is just as important as the attempt itself.
Yeah, just like how you can't tell players to 'outattempt the other team'. You need to play solid fundamental hockey and those things should come as a product of it. Obviously when a player is on the ice he's not thinking 'I need to outshoot the other team on this shift'.
The 'outshoot the other team' was moreso meant over a long haul not really a strategy to go into a single game.
Currently, the league average Shots on Goal per game (for a single team) is 30. 30 x 2 is
60
League average goals is 2.69. 2.69 * 2 =
5.38
Thats
60 vs 5.38 events to work with per game. I don't know the average shot attempts per game, though, but on the surface is seems like Shots alone should suffice. Goals is clearly too small of a sample to be predictive. I am obvsiously not a statistician though
EDIT: just realized this is counting special teams and all non 5v5 play so it's actually a smaller sample than listed