This statement is completely wrong.
I tell parents all the time: take one private a week, and go play matches. Sometimes I tell parents to take one private every two weeks. It's just overkill to do anything more until you reach the higher stages of the game (i.e., professional tennis). Players need to be playing 8-10 sets a week - that's where the real learning happens.
Developing young juniors need to have at least 1 lesson per week or better, 2 lessons.
Developing juniors should only be concentrating on developing their strokes, foot work and conditioning.
Practice sets should only be used to practice their strokes under pressure.
That statement will only develop pushers with bad strokes.