I learnt it from a chef in Japan in 2009, and I assume he had been doing it for many years at that time.
Generally, that’s something done at a sushi train restaurant where the dishes won’t have wasabi in them already. I’m guessing these notes are for a sushi restaurant where the chef prepares the sushi specifically for each customer, so if you wanted wasabi they’d put it in the sushi itself.
It’s just personal preference.
I learnt it from a chef in Japan in 2009, and I assume he had been doing it for many years at that time.
Generally, that’s something done at a sushi train restaurant where the dishes won’t have wasabi in them already. I’m guessing these notes are for a sushi restaurant where the chef prepares the sushi specifically for each customer, so if you wanted wasabi they’d put it in the sushi itself.