How will strength improve a slapshot ?
Theres a reason why golfers have mostly technique training in their regimen vs strength training, its because actual fitness has very little impact on how hard/far someone can drive the ball. The slapshot is literally the same movement pattern as golfing, there's very little muscle exertion going on in a those type of swings.
Even when it comes to much heavier implements, like the shot-put, weight-over-bar and even olympic weightlifting, technique makes up probably 80% of the athlete.
Think about it, why would you want to be supra-optimally strong when the thing you have to move weighs 160 grams ? The bulk of the force transfered in a slap shot (And a snapper, and most wrister) comes from the weight of the shooter, arms act as strings, rather than force producers.
How do you explain Elias Pettersson being one of the best slapshotter in the league ? This guy doesn't have one muscle in his body. Lmao.