... a guy posted on Saul's board:

discussion.fool.com - The most important lesson

What he found (long post, the interesting stuff are the tables at the end): IF his calculations are correct Saul himself(!) and the most respected posters with all their buying and selling did either not better or even worse than if they had left their portfolios from 1 year ago simply unchanged!

If correct this for me is a sensational finding as those guys are not just the average Joe who gets rather poorer as more transaction his portfolio has.

I think everybody who was/is a regular reader of that board respects them for their hard work to really analyze their companies in depth and for the concentrated knowledge on that board. Many are working in that field and REALLY know what they are talking about when it comes to the technology and the competitors. They are really doing what Warren preaches and stay in their area of competence. They are the experts. Not necessarily for valuation of that area, but definitely for picking in that specific area the best companies. And that 'picking the best, replacing by it the second or third best' led to no advantage over just staying with what they had 1 year ago?

If correct it leads to the question what chances any of us has to pick stocks in even different areas - without being an expert for this type of company, and that type of company and the next one might be interested in etc.