How do I answer that common question: ‘How much practice should I (or my child) do?’
The answer has a lot of variables. Young children and beginners would start with a small amount of regular practice and gradually increase it. For example a five year old beginner may do 5 minutes once or twice a day, an adult learning for a year may easily do half an hour a day.
There are some factors that can affect progress. In general, progress will be more noticeable if practice happens more often, not necessarily more hours. If you practise for a total of one hour in a week, you would be more likely to notice more progress if you played for 10 minutes, 6 days of the weeks than if you played for 30 minutes 2 days of the week. I don’t have the scientific reasons for this; I have just found it to be true in my own playing and that of my students.
Another important factor is the quality of your practice. If you are dreamily playing through your favourite pieces, that is a lovely enjoyable thing to do, but it may not be the kind of practise you would do to consolidate skills. If you are practising to learn something new or challenging, then you need to be completely focused on what you are trying to achieve and how to go about it.
Ideally, it is good to have a combination of all of the above. Practice needs to be both hard work and fun. It’s a wonderful feeling when you can finally play that favourite piece that used to be too hard.