Not sure if this is a trick, but a really valuable thing to learn is that the "sunny 16" rule is dead wrong for negative films. It's ok for chromes and polaroids, but results in dramatic underexposure of b&w or color negatives.
However, once you find out what your own personal "sunny" number is, it will be remarkably consistent. Using large format TXT and HP5 Plus my sunlight exposure is 1/8th @ f/45 if there are only small shadow areas, 1/4 sec if there are large shadow areas. Add another stop early or late in the day when the sun is near the horizon. Other conditions can be consistent as well. Overcast light can be dull and drab, but sometimes it can be wonderful and glowing: when it's wonderful, the exposure is a full second at 45. ---Carl