The FAA Office of General Counsel issues interpretations in response to requests for clarification of the Federal Aviation Regulations. These interpretations carry almost as much weight as the regs they reference, so pilots should become aware of them and how to research them. Here are some highlights which apply to us as general aviation pilots.
Ability to fly shorter than published leg lengths on some holding patterns
Neither a pilot nor their instructor are considered "passengers" for purposes of satisfying currency requirements to fly passengers during day or night.
A pilot and their safety pilot cannot both log cross country flight time even though they are both logging PIC time while the pilot is flying in simulated instrument conditions.
A pilot who builds flight time while someone else pays for the aircraft may be receiving compensation.
A parachute is not required for spin training for a CFI initial applicant.