A lot of it is luck with ending up with those extraordinary ones but you have stacked the odds in your favour by choosing good businesses. Still, your return is out of this world. You've mention various times that your style is to buy good businesses and hold them. In the long run though, I would not think it would be possible to sustain those levels of returns unless you sell out and invest the proceeds again. No business can keep pumping out 35% growth in the long run. You've managed to do it for 12 years now though, do you think you could sustain it into the future?
You are right my holding period is not 12 years on average so some return is probably attributable to harvesting earning multiple changes and re-investing and into fresh undervalued opportunities. I never thought I could archive it in the first place so I have no expectation of it continuing. In a burst of ego driven overexcitement I have recently lifted my future expectations of a real 3% return after inflation, tax & expenses to 4%. The extra 1% real is what I think I can add long term for stock selection & portfolio management.