I know because I am consistently running up against real issues that involve things I've learned. It has been very helpful, even in the minimal case of providing a frame of reference for making decisions.
Joe Kraus' emphasis on "make what you measure" convinced me to start measuring some specific metrics in more detail. The end result was boosted numbers in some of my performance/growth stats.
The most valuable things I've learned from other entrepreneurs are principles and methodologies. I apply them over and over again as I face specific issues.
