Quran Life treats daily portion cycles as the phase where the sound and broad flow of the surah settle into memory.
For many people, something like 2 to 3 cycles is a reasonable point before selective rote shortcuts start becoming useful. But that number is not a law. It depends heavily on the person and on how much prior contact they already had with the surah.
If the surah already feels half-known, rote reinforcement can come earlier. If the surah still feels foreign, even 2 or 3 cycles may not be enough yet. The practical question is not whether rote repetition is allowed. It is when it stops being a shortcut and starts becoming a crutch.
If the cycles have already made the surah familiar, a small amount of rote reinforcement can be efficient. If there is still no structure or familiarity, rote repetition often creates shallow recall.