Well OP, I think we’ve established that there are a range of very valid views on this.... the key points and phrases to me are:
-‘If a child is to reach their potential’ (some will have huge potential but neither the will nor the time to get there)
-little and often is better than none
-it depends on age and standard
-it depends what the goal is
-it depends on how fast your kid learns!
I was a bright, natuarally able child but wasn’t great at putting the hours in to focussed practice, although I played for many hours each week in lots of orchestras and ensembles. I got 2 grade 8’s by 18, taught myself a range of other instruments and got an A at A level music, but didn’t pursue music as a career.
DD is 11 and has already surpassed me as a violinist. She learns at a JD, has a regular practice routine (as previosuly mentioned, 45-90 mins per day on violin) and wants to be a professional musician.
I would say we both have/had the same aptitude for music, the differences are that she is more of a worker and has a Mum who is able to support practice and helps her to make the time to facilitate her training and development.
I also have DD2 whose practice regime is more erratic. She probably does 15-20 mins 3 times a week. She still progresses, although not as fast as her sister did at the same age and her technique is not as well embedded. She is generally a less reliable player.
If the aim is recreational music, then a few minutes each day spent well, supported eventually by ensemble playing and development of musical awareness will result in a competent amateur musician.
However, I have never come across a professional musician (and we know many) who has made it without putting in hours of daily practice at some point in their lives. Even the most gifted only develop the muscle tone, memory and stamina required by putting the time in.