Yik Gun Ging was supposedly the most important martial art skill to originate from the Shaolin Temple. It was certainly the most coveted.
That being the case, why did not a single Shaolin monk (i.e. aside from maybe the Chief Abbot in SPW) in any of Jin Yong's novels train in this skill?
In DGSD, the Yik Gun Ging was sitting there in Shaolin's library until Ah Chu stole it, but no Shaolin monk (aside from maybe the Janitor Monk, but that's just speculation) ever trained in this skill. Why? Was it because nobody at Shaolin could read Sanskrit (unlikely, as there were so many learned Buddhists at Shaolin)? Was it because nobody had the talent to learn it (was it really that hard to learn)? Was it forbidden by some rule (that would be stupid; forbidden to learn one of your own sect's skills)?
Shaolin wasn't heard from in LOCH or ROCH, but in HSDS, Shaolin's most coveted martial art was the *partial* 9 Yeung Jen Ging it gained from Mo Sik's memorization of Gok Yeun's final recitation of the manual's text. The 9 Yeung Jen Ging wasn't even a Shaolin creation (until the retcon introduced in HSDS Ed. 3, it wasn't even a Buddhist creation) and yet, the Shaolin monks of HSDS gave this partial manual that their sect didn't create preference over their own Yik Gun Ging? Weird.
For a martial art that was supposedly Shaolin's best, the Shaolin monks certainly didn't treat it like something they greatly valued.