Lesson:

For every 1 right hand shot, there's 2 good left hand shots available in every role, and at every position
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As long as you get what you want, nothing else matters.

But you need to know your alternatives and your competition to make sure you're not left out.

The teams that like to win the Stanley Cup know they need to be resilient against injuries, slumps, or opposition targeting. You need R/L balance to enable line shuffling.

Why not just have all left hand shots if they are plentiful and cheaper? Goalies' glove is on the wrong side for righthand shots, strong side faceoffs, quicker puck movement and one-times without getting out of position between L+R shots.