I don't really buy that. If you're a Jedi, you're already trained in the Force to some degree. Luke picked it up pretty quick. So did Rey. I'm sure others have taken longer. Force push/pull abilities are mind over matter abilities that a Force user already possesses. It's why Yoda tested Luke by telling him to move the X-wing out of the swamp. He hadn't been training long, yet Yoda understood that Luke was powerful, but not yet ready, not because he couldn't wield the Force, but because he wasn't ready to face Vader.