After you've spent a few days checking up on the work you did during the day you may start noticing some problems for the first time. Typically, students--- those that practice consistently and regularly--- tend to practice the very beginning of each piece more than the rest of it. They tend to get stuck on the first difficult passage, and give it a lot of work, while the ending of the piece, being one of the most important parts of any piece of music, gets relatively neglected. They also tend to leave a lot of their music in the beginning stages; practicing it, but never making the jump from plodding along just reading and reacting to the page to actively trying to reach an ideal musical goal.
For now, I will hold off on giving any specific tips on practice time management--- hint: it involves making a schedule--- but try and plan what you are going to do each day before you actually go into the practice room. Just sitting in front of the piano and "going with the flow" is good to do sometimes, but if you make that your daily routine, I don't think you'll be getting a lot of work done.