Hi Faa2010
For me, it depends on how difficult the piece is and the different techniques required to play that piece. I am not happy even to go to the next page of any piece until I have learnt ninety percent from memory.
Fortunately for me, because I am not constrained to any music school or exams (except for my weekly lesson), I do not think in terms of time when learning or finishing a piece, rather, when I am "satisfied" that I can no longer draw anything else out of the music. But I am never satisfied that I have finished any piece.
All the Best,
Энтони.