Although this can often be determined by organizational or financial circumstances, a child (4-10 years) benefits most from 30 minutes twice a week!
You’ll probably wonder why this lesson length with a total of 60 minutes isn’t more expensive than the one with 50 minutes once a week.
It’s quite simple: a higher lesson frequency (twice a week instead of once) with shorter duration generally yields faster progress and usually leads to more motivation and joy, this I’d like to support wholeheartedly.
Experience also shows that more frequent lessons and shorter Intervals in between lessons are highly beneficial for children. Besides, few younger children have an attention span required for a full 50-minutes-unit.