Yah, It's pretty much been said that theres a a possibility that kakashi's and obito's sharingan are linked and since obito has hashirama's cells which prevents the degeneration his sharingan perhaps it is this link between them that prevents kakashi's sharingan from degrading as well
i wont really say sasuke is spamming the one that is really spamming is Minato...the only useful that minato has done is use use and overuse his space time teleportation technique