To me this discussion goes back several days to a post that sugested something like a wannabe photographer should learn to see or read available light to make good exposures without a meter. This is possible and has worked well for me for over fifty years, the missing link is that folks that use the "Sunny f16" rule often do not learn to really see what is necessary to make it work. One must learn to interpret the shadow regardless of how high or low the sun (main light) might be. I don't intend to give you any short cuts in learning to see light or read shadow because I don't think there are any. I believe only experience can teach this. What is bright sun light? ask that question and most likely you will get several answers. For my self on a bright sunny day I look into the shadow, fence post, telephone pole, tree,
side of a building or the triangle shadow right under a persons chin. Makes no difference, the shadow will tell you its story. You will see absolutely no detail in a shadow cast on a truly bright sunny day. I f you can see detail in the shadow it is not being cast by a bright sun, clouds, atmosphere, dust or whatever is diffusing the sun. The more detail you can see in the shadow the
less bright is the sun. That simple! Kodak's rule will work today if you use it
properly. Look at the subject determine if you can see detail and how much, or is the shadow soot black. If there is no detail, you'll have to modify your exposure to achieve the image you want. The zone system addrersses this.

Part of the Kodak rule says: Expose with the sun directly behind or over the shoulder in front light, If the sun is lighting your subject from the side, give a half stop to a stop additional exposure. If backlighted give a stop and a half to two stops additional exposure. Rule of thumb has been challenged in this thread, but most rules of thumb I have found, were based on proven fact.

These old wives tales when properly interpreted and executed can give you excellent results. I learned to see and understand light and shadows in a time when exposure meters did not exist. Photography was all seat of the pants, even Ed Weston did not use a meter until much later in his photography. Today I see no reason to own a meter and not use it. Few
meters get it right every time, you have to learn to interpret the meter and when to overide it. The gray cards I use do read 18% reflectance gray, somehow I have it in my mind that if it reads 12% it isn't an 18% gray card.
regardless correct exposure can still be interpreted from it with a few adjustments.

Making good negatives can be made without all falderah and fiddle faddle. There is in my mind no short cuts, simple hard work will get you the experience to make good exposures under any lighting circumstance.

Available Dark, has caused me many problems in my life however.