To each his own pursuits.
I would think that an aircraft spotting log could pose many error problems, producing suspect personal databases. Railroad boxcars/tank cars/flat cars/automobile cars, etc at least in America don't change serial numbers per Interstate Commerce Commission regulations, but many aircraft are re-registered with change of numbers, some many times, or many aircraft have had the same registration numbers. Our US FAA database is rife with examples. And, refinishing an aircraft can change its appearance. For example, one would never think that N7813N is a 1974 aircraft, with its later refinish it looks new.