...and why is that the best technique?
This question seeks the pros and cons of different techniques for shaking the can. What's more effective? What's less likely to cause injury (including injuries from repetitive movements)?
This is not intended to be a subjective question or one based on style, any more than a question of "what is the best way to lift this heavy weight?" or "what is the best way to connect these wires to this outlet?" There are some ways that are clearly better than others, and the reasons are not necessarily obvious, but someone who has a lot of experience with the subject might have figured out which ways are better than others.