A Japanese philosophy, seems relevant in the current state of our world.
Mixing wasabi with soy sauce is known as wasabi joyu, an amalgamation of the words wasabi and shoyu the Japanese word for soy sauce. According to Sushi Sasaya Korin, wasabi joyu is a violation of etiquette not only when it comes to sushi but all Japanese food in general as the two should always be enjoyed separately.
I prefer it mixed.
If the chef uses the right amount of wasabi just a touch of soy sauce is all that is needed. I learned the hard way about etiquette of sake, if you don't flip the cup over they keep refilling it and expect you to drink it. My Japanese customers were delighted to get me really drunk. We had some wonderful regulars, one was an executive that I took to rock and roll bars a couple of times for live music. I managed to get him to safety when the crowd started slam dancing.
Ichi-go ichi-e and easy on the wasabi.