For Parents > Driving Schools 
Each child is different, as is each parent. Some students will learn very quickly while others will take a lot longer, yet still get there. Supervising can be very frustrating, especially when you, as a parent, know how to drive but not necessarily how to explain what you do.

Here's a basic plan for interacting with a driving school. Please consider it and modify it according to your student's needs, your budget and your own expertise and availability.

Early days
Choose a driving school. Establish a rapport with your child's professional instructor. Ask for feedback and suggestions about what to practise. Three to five lessons is a good start, teaching the basics and getting them off on the right path.
In this period every drive is undertaken for the purposes of training, whether it's a driving school lesson or a parent lesson.
The middle period
A learner must hold their licence for twelve months, so it's a long period of training. After mastering the basics and becoming a "capable learner", I'd recommend the occasional professional lesson. If you can teach reverse parks and head checks, go for it, but the student needs to acquire good skills during their training, not in a rush at the end.
This is what I call the "practice period", as opposed to the prior "training period". Shopping trips and visits to relatives can be used to accumulate many hours of driving for the student, at virtually no cost to the family budget because the trip was planned anyway.
The last month
Around a month before the student wants to do their test is a good time to book another lesson. Your instructor should be able to fine-tune the student's skills and do a mock assessment, so as to give you some idea of how ready they are. Of course this could lead to other lessons, depending on the student's driving standard.