If you do not practice properly, you probably won't get any better. You'll probably say "that instruction doesn't work" (even though you're not doing it).
The worst culprits are often the better players. They make two swings slow motion and think they have it. I'm easy at first, gently reminding them. Then I get a little firmer. Then firmer yet.
But ultimately I can't go full drill sergeant on them, and whether they practice properly after having the benefits, reasons, process, etc. explained, it's up to them.
Oh, and… the title?