First of all, the amount of practice required is a little different for adults and children.
For example, a parent recently asked in relation to her 7 year old daughter…
“I want to ask your opinion if a practice of 30 minutes 3 times a week would be fine to keep progressing?”
As a general guide, the same amount of time spread over 5 days (e.g. around 10 to 15 minutes per day) would be our ideal suggestion, especially for children.
That said, it really boils down to what works best for your child, and if 3 x slightly longer sessions works better for your family, that's perfectly fine.
For young students, around 90 minutes or so per week is a good level to aim for and hopefully will be sustainable.
The same parent went on to ask in relation to herself…
“For an adult (I am 44) how much practice do you think I might need per week/day to get good progress?”
This is a good question. Of course, the more the merrier, but there are many different considerations that go into the optimal practice routine for each adult student.
In some ways, practice is like pruning hedges – “little and often” is the key.
This approach (a small amount several days a week) is definitely preferable to one or two longer sessions per week, especially in the early stages. But ultimately, the best arrangement will depend on your individual circumstances and what works best for you.
For beginner adults, if you can possibly manage 20-30 minutes a day 5 days a week, that will see you progress nicely. Then, as you become more advanced (e.g. Level 10 of the Musiah course onwards), if you can manage it, it would be great to increase this gradually to about 1 hour per day, 5 days a week.
This way, you will progress very well indeed, but even if this amount of practice is not possible, that's OK. Just do what you can, and you will still get there. It may just take a little longer, which is perfectly fine. After all, learning how to play the piano is not a race.