There was a crash of a turboprop several years back that was attributed to the aircraft being way overweight (and out of CG limits) because they used 50 year old average values for passenger and baggage weight. The average values were updated as a result of that crash, and those numbers are now periodically reviewed and updated.
BTW, many years ago I arrived at my destination for a ski trip and was one of about 20 people whose baggage hadn't been loaded because they otherwise would have been overweight (737-200). Tough to go skiing without gear
