First of all, this is great post. Your mentor's strategy is probably tempered with real life experiences that give him a roadmap for the future. At his level (and probably age) there's no reason to expose all of his wealth to market uncertainty.
In terms of preservation, I try to build a motte around my investments to protect them from the market and potential liability exposure.
I hold my properties longer than most of other investors that I know, this helps insulate my properties from market fluctuation. As you know, you make your profit upon purchase. I try to have my lease agreements shift most of the responsibilities from my companies to the tenants, make sure my LLCs are sound and that my commercial insurance policies cover the "unexpected" events that could go wrong.
That being said, every plan has a weak point. You need to be flexible enough to adapt to the situation to overcome it. I like having a couple contingency plans in place. My favorite contingency is you can never have enough cash on hand.
-John