Today I have begun my new practicing routine. I practice the difficult pieces for 30 minutes with a break after 15 minutes. I work on a few sections with my right hand and left hand alone and slowly. Throughout the day, I practiced only 15 minutes on the medium pieces(pieces I have already worked on and can play with both hands). I was able to practice 4 pieces today. And did 10 minutes of Hanon and 15 minutes of Czerny. So altogether I practiced 1 hour and 40 minutes. I like the breaks after the 15 minutes of practicing so that my mind can relax and do something different. Some days I may have more time to work on the 30 minute difficult pieces and I have 3 of those which requires some "hand memory".
Last night I have read some of Bernhard's posts and gained some insight about practicing effectively. I don't have to sit for several hours to learn a piece. I like his concept on practicing in small sections at a time each day with separate hands until the piece "experience no technical problems." And he mentioned: "Practice not to get it right but to never get it wrong."
It seems to me that Bernhard has brought the essentials into my practicing. I haven't had a teacher for so long and it's great to read something that will help me.
Where ever he is, a big thank you! 
best wishes,
go12_3
go, I think one of the essentials mentioned above was "goal-oriented" practice. When bernhard makes his posts about time, he means finding a goal that will take that amount of time or less, not practicing for a certain amount of time and then stopping. You should always practice until you have achieved your goal. Therefore, I would like you to mention your practice in no. of bars practiced (and what you did with them, if you want to get specific), not time spent on a certain piece. Those are goals, not just "putting in the time".
Second, what it seems you missed in bernhard's posts is that slow practice is a problem. There are two purposes for slow practice: to ingrain movements required for fast practice, and *extremely slow* to check memorization. Bernhard talks about both of these. The majority of practice should be at speed or faster to ensure you're using the optimal motions for performance. Slow practice is not for learning passages. My advice for this is to use backtracking (one of my favorites). Step 1: Metronome ON, Step 2: Play the last note of the passage, until it is comfortable (not too hard), Step 3: Add the next note in front of that (a little more challenging, but not too), Step 4 and on: Keep adding notes on the front until you have the whole passage. Notice that this is note by note, not beat by beat. Also notice that this can be done both HS and HT.
Third, HS is a practice *tool*, not a first go-to when practicing. The goal is HT, and so you should do your best to learn HT first. If you find that your technique is not capable yet, that is when you go to HS. Review bernhard's posts more closely, as he gives a list of problems he defines as "technical", i.e. requiring HS practice.
Fourth, you can practice for up to forty-five minutes at a time (obviously not on one piece) before a break is necessary. Breaks should be about fifteen minutes long (we're getting into psychology here). You should be doing something other than thinking about piano during these breaks. Also, understand the goal-oriented nature of bernhard's practice system. I sometimes practice for much longer than twenty minutes on one piece, but during this I am iterating the following: learn a section of music, and connect that music to the previous music learned. I do not spend forty minutes pondering over the same eight-bar phrase. If I can't play it by then, it gets broken in half, sometimes even bar-by-bar, until I can play it at tempo. This takes less than forty minutes for eight bars, normally.
Fifth, I agree mostly with Ramsey. I do believe, though, that while you are learning a passage you must practice it every day. This is because a ton of reinforcement occurs during sleep each night, and you want to ensure that happens daily for optimal progress.
Sixth, as a few have mentioned, music is the main objective. The stuff I have mentioned above helps you get there, but it is still about the music. Don't lose perspective when working on the details.
Finally, you are missing one of the essentials: a
teacher. We can tell you all you want, but we can't show you (Webcam's not clear enough), we can't move your arms for you, or, for that matter, your wrists or torso. You need some one in person who can show you the right way to do everything.
For further reading (since you seem to enjoy it): Indispensables of Piano Playing by Abby Whiteside or Mastering the Chopin Etudes by Abby Whiteside. For all the obscurity in her writing, her description of the proper coordination when playing piano is very accurate. I don't agree with everything she has to say, but it's food for thought.
Topic: What is essential in practicing?