Fruitful practice at home is the result of what the teacher does at the lesson.
The student should be prepared to practice correctly. He/ She should be ready to concentrate and not to expect perfection immediately. The student also needs specific techniques that he/ she can draw on while encountering a problem. It's the teacher who have to teach him/ her these things.
Practice is most effective if the student works with specific goals for the session. Those specific goals most often translate into specific areas. It is surprising that in very short order the teacher and the student are perfectly in sync with the number of repetitions that are needed for an area. Sometimes the student can practise single-handedly first.
If the student is a child, he/ she may need parent's help.
'Pratice makes perfect.' Take time and effort to structure the piano study so that home practice is as effective and as productive as possible.