So, when you see a vid of a Korean club and you get to see deep double digit of players, you can get a feel for what it is like over there.
KJH by the way, is kinda like the old school coaches in teaching the BH in that he is more inclined to train the amateur player to make the first offensive response vs an incoming weak or medium underspin ball by using the FAST LOOP or LOOP DRIVE (fast ball speed maybe medium spin).
He DOES teach the slow/heavy spin loop we all know, but his progression is the loop drive first.
At the pro level, spin is nice, but many feel they have to play fast.
Myself, I was way different, I was spin first. When I went to Korea in 2009 as a RECREATIONAL PLAYER of maybe average Korean club level, I had the most spinny BH loop vs an underspin in the entire city as a Div 4 level player. That city had a half million population and maybe 100-200 players who were better Div 4 or higher level players than me.
That is remarkable that a dude, a fat 40 yr old dude, a rec player walking into the club right off the street with ZERO prior coaching would have the city's best BH spin loop vs a cut ball. They just never saw amateur players do that - it amazed them, it froze them and they would block the ball out and long, even the Div 1 players who were WAY better players than me. Even more remarkable is that I learned my spinny BH loop simply by reading Larry Hodges TT Book that teaches the basics of TT... and playing some rec center matches in Iraq the second time I was there.
That is the degree that the BH topspin heavy loop was not used or taught. No coach taught it or did that shot... it was all BANG BANG go for speed. At the time, there simply wasn't much teaching and coaching of the attacking BH for Shakehand players. You kinda figured out how to do that if you made it to Div 1 and got better touch timing and goofed off to learn it.
The predominate teaching of the BH in general at that time was similar to penhold concept in that the use of the BH was to be consistent, keep ball in play, away from opponent's strengths, and then seek a chance to step around and use powerful macho man FH kill.
... and this was just 10 years ago !!! In a nation with great pro players.
At about the same time, you had a lot of retired pro players who were shakehand and could play with some spin... and teach it. These all made their way to clubs as assistant coaches or club owners/coaches. It took some time, but now, on youtube, you can see all manner of ex-pro, ex semi-pro, and the pro-trained crowd teach all kinds of wonderful SH topspin play technique.