If you want to practice efficiently: to make the best use of your practice time in order to conquer the difficulties that make you stuble, you should read this free book: Fundamentals of Piano Practice by Chuan C. Chang.
One technique I recall from the book is to objectively identify the difficulties in a piece. At some tempo, you can play the piece without making mistakes, or just with some rare blunder that could happen anywhere. As you gradually speed up the tempo, certain parts can be sped up easily, but some passages expose themselves as stress points. When you try to play these at the increased tempo, you stumble, miss notes, or turn the passages into gibberish.
Once you know where the stress points are, then just practice those stress points.
To discover the stress points properly, meter an exact tempo with a metronome. Your tempo has to be even because you might otherwise subconsciously slow down around the stress points. The metronome reveals everything in numbers: it tells you that you could still play the whole piece at 90 bpm, but at 110 bpm, you stumbled at bars 17 and 29.
Chang, by the way does not recommend continuous use of the metronome during practice, but rather as a tool for this kind of thing:
"Metronomes should not be overused. Long practice sessions with the metronome accompanying you are harmful to technique acquisition and leads to non-musical playing."
Chang argues like this: if the piece is five minutes long and has one stress point in it, you will only hit the stress point twelve times in one hour if you simply practice the piece by playing it over and over again. But if you practice just the stress point, you can hit it several hundred times in the same hour. Don't waste time practicing what you already know very well, in other words.
Always practice the stress point together with some notes before and after so that you're rehearsing the entry and exit transitions which connect it to the rest of the piece.