Back in the day--I'm talking back in the 70s--a lot of natural light photographers became wizards at working with what was called "subtrative lighting."
That was the technique of using scrims or black "flags" to remove or weaken lighting from one side of the subject so as to create directional light from the other side.
You can see this happen if you take a subject in open shade, such as cast by a building, and move the subject close to the wall that's casting the shadow. The wall will cut out even more light, and suddenly you have a broad, soft light on the open side with shadows as deep as you want them on the side close to the wall...just move the subject closer or farther.
An overcast day normally creates racoon-eye shadows. But put the subject under an overhang to cut the overhead portion of that light, and you get nice sidelight or broad frontlight. Box the subject on top and both sides, and you get the effect of standing in front of a huge umbrella.
No building nearby? That's when you used the black surface of that 5-in-1 reflector.
This was a rather difficult technique back in the 70s because films were slow--subtracting light when you're already in a dim-light situation meant long shutter speeds. But with the ability to easily shoot ISO 400 or more and with IS lenses, it's something more photographers should learn.