She was masterful – she used to say, wistfully, “Even if I had to pay them, I’d need to do this.”
She had two rules:
She would not accept anyone who didn’t have access to a piano outside the lesson.
If her students showed signs of not having practised since the previous lesson, she sent them home to practise.
….and it seems to me this is what we should be doing as language teachers. Without practice, it’s merely theory….