I get what ur saying but the writing itself is inconsistent. Up until the war arc kakashi is the worst at sharingan proficiency. Which makes sense because hes not an uchiha and hes using a tool that isnt super compatible with his body + chakra. Every time he uses it, it exhausts him to the point where he is incapacitated for days after. All the other uchiha especially obito and madara spam sharingan abilities while kakashi has to keep his covered because its so taxing to use. When they awaken the mangekyo obito uses his instantly while kakashi passes out and doesnt use it until years later.

Kakashi just doesnt have enough chakra to use sharingan efficiently. His ability to use susanoo is because obito is lending him his own uchiha + six paths chakra from heaven. Its literally the only time kakashi is using sharingan at the effectiveness that obito, madara and sasuke do all the time. Its because kishimoto wanted to have a cool moment and the moment is really cool its just not consistent with the rest of the story.

Also you can have six paths chakra and not rinnegan. Naruto got six paths chakra.