I've been wondering the same thing. In my mind I'm always on the fence on the idea of purchasing Syoei's videos myself because I thought "oh, he's popular anyway, these vids will be out soon". But it's true, there are not many of his that actually got leaked.
At first I thought that was because some of his videos belong to the Japan-exclusive label "Dream", these are supposedly slightly more complicated to buy if you're outside the country (although not impossible), so maybe they're just lazy.
But then the "Cruising" and the edging concept videos are practically available globally.
I also notice that the videos for Ryosuke/Minato
almost always got leaked either the same day or just 1 day apart from the day they got released, whereas other leaks are inconsistent. So could it be just a matter of the leakers' taste/preference? Who wouldn't like Syoei tho, Idk