Feedback is more important than new teaching - this can be understood by thinking about an extreme case: a student who will usually forget the new learning that they learned last lesson.
If time spent each lesson re-teaching or reminding the student what they have forgotten will mean that soon the student will able to recall that learning in the future, then that time is well spent.
In an extreme case like this - we may need to remind students more than once about any single layer before the student can remember between one lesson and the next what they learned.
However as timely practice does it's primary job, embedding learning, less time and effort will need to be spent each lesson on re-teaching or reminding that layer until before long the student can remember that learning between one lesson and the next.