I think it is due to the part of shadow clone training that kinda gets forgotten with the knowledge transfer. I'm talking about how not only do you get the knowledge of the clone when it disperses, but you also get the clones fatigue. Sure you can make 9 clones and train for 1 hour then disperse them and get the knowledge benefit of training for 10 hours, but you also get the sudden fatigue of doing 10 hours worth of work in under 1 hour.
Naruto has extremely fast healing and a lot of stamina/chakra due to Kurama and his own natural ability (son of Minato and reincarnation of Ashura), but even he passed out from having too many clones just cutting 1 leaf in their hand then disperse (Shippuden ep. 73).
Due to the fatigue transfer, I think Sasuke may have been worried that it would affect the lifespan of his eyes before he got the Eternal Mangekyo Sharingan. Afterward, I think he just felt he didn't need the technique, plus he associated it with Naruto and his fear of loneliness.
With Kakashi, he just uses so many chakra techniques and would copy techniques on the fly, so it was almost always a better move to keep his chakra pool as large as possible to be able to use whatever technique he would need, and he doesn't have the chakra or stamina of either adult Sasuke or Naruto.
And why neither of Naruto's friends from Team 11 seems to interest in learning this jutsu?Kiba knows the shadow clone jutsu but because of his low chakra pool, he can only make 1