"You just gotta get stronger to skate faster."
It's a training mantra repeated ad infinitum in sports.
I agree with it.
And I also disagree with it.
But before we tackle that statement, let's define the three most important forms of speed work for a hockey player so that we're on the same page moving forward:
The distance over which an athlete is able to accelerate prior to reaching maximum velocity.
Skating at full speed.
Rapidly decelerating and accelerating in a different direction - forward, backward, diagonally or laterally.
With these definitions out of the way, let's talk more about physical strength and how it relates to speed development.
As a beginner, nothing will improve your skating speed as much as gaining lower body strength will.
(Apart from improving your skating technique which takes place on the ice, not off the ice)
Research is pretty clear on the benefits of increasing leg strength for acceleration and change-of-direction performance. [1-5]
The closer you get to reaching your strength potential, the less impact maximal strength gains will have on your speed and power.
Don't believe it? Here's one example:
A study done on D1 American football players concluded that increasing strength improved speed (40-yard sprint time) and power (vertical jump height) for about the FIRST YEAR.
Gaining more strength did not significantly increase the athletes' speed/power. 
Furthermore, it takes EXCEPTIONALLY large increases in 1RM back squat strength (23-27%) to only slightly increase sprinting speed (2-3%) in intermediate/advanced athletes. [6, 7]
This means an imaginary hockey player who squats 160 kg (352 pounds) and runs a 4.00 30-meter sprint today would need to bring his squat up to around 200 kg (440 pounds) to witness his 30-meter time drop down to 3.92 seconds.
A 40 kg INCREASE in squat strength would produce just a paltry DECREASE of 0.08 seconds in short-distance sprinting.
From 160 to 200 kg. That's a two-year adventure, minimum. Longer if you play hockey at a high level.
(Less time for off-ice training the higher the level of play)
Not only that, there's no guarantee that the 0.08-second improvement in running will transfer into skating (where it REALLY matters).
While there's a strong correlation between dryland and on-ice sprint times, improving one doesn't automatically improve the other.
So even if our imaginary player managed to eek out a small sprint boost through strength training, he may not witness any change on the ice.
All that time invested and the increased toll on your joints in return for miniscule speed gains?
Not a very profitable training ROI in my books.
Especially considering how professional hockey players can improve their 30-meter skating times up to 0.277 seconds in only 13 weeks by using a combined strength + speed/power training approach.
If more strength isn't the answer, then what is?
The more informed athlete will turn his sights to jump training to enhance his skating speed and explosiveness.
Enter box, depth, broad and vertical jumps.
But is that really the optimal solution?
How well does bilateral power training transfer into skating?
What about the DIRECTION of force production?
Skating takes place HORIZONTALLY. But common VERTICAL jump exercises like box and vertical jumps continue dominating off-ice training programs.
Is their inclusion warranted? Or should we do something different?
I've been questioning the over-reliance on bilateral vertical exercises in unilateral horizontal sports (like hockey) for some time now.
And interestingly, research seems to agree with what I've noticed in practice. Check out these few tidbits on improving speed over short distances (a.k.a. ACCELERATION):
#1. Increasing maximal sprint velocity appears to be more dependent on HORIZONTAL rather than VERTICAL force production. [8, 9]
#2. Enhancing sprint performance – especially over short distances – comes down to improving an athlete's HORIZONTAL force production capability. 
#3. Because skating is a horizontal activity, increased HORIZONTAL LEG POWER plays a crucial role in skating faster. 
What about CHANGE-OF-DIRECTION SPEED then?
Same story as above:
Traditional strength and power training programs involving mainly bilateral vertical exercises (i.e. Olympic lifts, squats, deadlifts, vertical jumping) don't elicit huge improvements in change-of-direction (COD) performance. 
A potential reason for the gap between strength in vertically-oriented exercises is the LACK OF SPECIFICITY to horizontal planar movement. [13, 14]
How do you improve change-of-direction performance then?
By using exercises that more closely mimic the demands of a COD, including:
The last two items listed shouldn't be too difficult to understand.
Sport-specific change-of-direction training for hockey is simple:
It takes place on the ice. And involves powerful acceleration and deceleration over short distances in multiple directions.
One way to do that is by accelerating back and forth between blue line and red line, or blue line and blue line.
General COD training off the ice isn't hard to grasp either.
Something like the pro agility drill they use at the NHL Draft Combine works well.
You could also use the L-Drill often seen in football preparation programs.
Or running 5 meters backwards, then exploding laterally into a sprint for 10-20 meters.
The variations are pretty much endless.
But what about unilateral + bilateral horizontal and lateral jump training? Or loaded vertical jumping?
How do you fit them into a comprehensive speed/power workout plan?
Let's talk about that now.
#1. Past a certain point, more strength isn't the answer for speed or power gains.
#2. The ability to produce more force horizontally (and doing so rapidly) should become a focal training point for any hockey player who wants to skate faster.
#3. For increased acceleration and change-of-direction speed, you'll want to use more unilateral and bilateral horizontal and lateral jump variations rather than sticking to bilateral vertical movements.
 Keiner, M et al. Long-Term Strength Training Effects on Change-of-Direction Sprint Performance. Journal of Strength and Conditioning Research. 2014 Jan; 28(1):223-231.
 Wisloff, U et al. Strong correlation of maximal squat strength with sprint performance and vertical jump height in elite soccer players. British Journal of Sports Medicine. 2004 May; 38(3):285-288.
 Mackala, K et al. Selected Determinants of Acceleration in the 100m Sprint. Journal of Human Kinetics. 2015 Mar; 45:135–148.
 Watts, D. A brief review on the role of maximal strength in change of direction speed. Journal of Australian Strength and Conditioning. 2015 Apr; 232(2):100-108.
 McBride JM, et al. Relationship between maximal squat strength and five, ten, and forty yard sprint times. Journal of Strength and Conditioning Research. 2009 Sep; 23(6):1633-1636.
 Jacobson, BH et al. Longitudinal Morphological and Performance Profiles for American, NCAA Division I Football Players. Journal of Strength and Conditioning Research. 2013 Sep; 27(9):2347-2354.
 Cronin, J et al. Does Increasing Maximal Strength Improve Sprint Running Performance? Strength and Conditioning Journal. 2007 Jun; 29(3):86-95.
 Randell, AD et al. Transference of Strength and Power Adaptation to Sports Performance-Horizontal and Vertical Force Production. Strength and Conditioning Journal. 2010 Aug; 32(4):100-106.
 Brughelli, M et al. Effects of running velocity on running kinetics and kinematics. Journal of Strength and Conditioning Research. 2011 Apr; 25(4):933–939.
 Buchheit, M et al. Mechanical determinants of acceleration and maximal sprinting speed in highly trained young soccer players. Journal of Sports Science. 2014 Dec; 32(20):1906-1913.
 Farlinger, CM et al. Relationships to Skating Performance in Competitive Hockey Players. Journal of Strength and Conditioning Research. 2007 Aug; 21(3):915-922.