"A good strategic planning does not necessarily copies theories & principles presented by various experts." What do you think? agree or disagree

Yes .. I fully agree with this and Iam totally against the copy/paste practice of what others said or did.

In fact, I am a100% supporter of "ROOTS-UP" approach stemming from specifcs of the organization (company) we are dealing with, build it up specially for this specific company, and use expert opinions and best industry practice as a guideline

Let me quote two examples

1. While the Kaplan/Norton methodology suggests a  four perspective balanced scorecard/strategy map, I very often encourage the customer to consider something else, like a3-perspective,5-perspective,6 perspective or even7 perspective view balanced scorecard/strategy map  based on what is best fit for the customer specification.
2. While everyone focuses on key performance indicators (KPI's), I do encourage my clients to start with Key Results Indicators (KRI's) first, because this is what really matters to external beneficiaries outside the department/function/unit in question (which means internal/external customers of this specific function/department/unit).   This is what they are concerned about, they really want to see results and do NOT really care more or less how these results were achieved as long as they are within the requirements/expectations 
3. Some clients go wild with the subject of KPI's .. dealing with every performance metric (PM) as a KPI ... something which fires back and confuses everyone involved in this system.  I in fact recommend anywhere between5 and10 KPI's and a similar or less number of KRI's that need to be selected carefully and within reason/justification.  I may even go to the extreme of focusing on one single KPI/KRI as British Airways did once to get this KPI/KRI achieved and get one of the most notorious problems out of the way !

Hopefully this answeres your question

If you need to know more, let me know !