Years ago, I build a large wall out of 2x4s and fastened them together with those black drywall screws. (About 3 inch long). I built it on the ground, and when it was complete, I began to lift it into place, like I had always dont with walls that I formerly put together with nails. Well, when lifting the wall, it flexed, and seconds later I had a pile of 2x4s laying all around me and several that were resting on top of my body. I quickly learned (the hard way), that those screws are NOT made for Structural Construction. They are very brittle and break as soon as they are stressed (such as lifting the wall in place).
After cussing a lot, I had to rebuild that entire wall, using nails. I have stuck with nails ever since. Over the years I've been reminded about NOT using those black screws for Structural Construction, while having to repair things built by other people who used them. In fact I bought a shed that was for sale and needed to be moved. I was preparing to move the shed, jacking it up, when the shed walls began coming off the shed floor. Sure enough, the builder had used those damn screws to attach the walls to the floor. We had to add lots of nails before moving the shed, or it would have been in pieces real soon.
Anyhow, recently my neighbor built a fairly large canopy to put over his door, and prebuilt the whole thing on the ground, complete with steel roofing. He got it done, and found it was too heavy for two men to lift above his door. So, he came to me, knowing I have a tractor with a loader. I took the tractor and lifted it above his door. He shot several of those gold colored deck screws into the house, and propped some 2x4's under it until the permanent posts could be placed. I lowered the tractor loader about 6 inches as the guys tried to raise the front edge of that canopy with the prop 2x4s because the front was too low.
It was fortunate I had not removed the tractor loader, or someone could have been hurt, not to mention damage to the canopy, because it fell right off the house wall. The cause was those deck screws snapped.
I was a little surprised myself. I thought deck screws were stronger than those black drywall screws. I guess I was wrong. While they probably are somewhat stronger, they are still brittle and they will break.
We got it back in place, but used 16D common nails the next time and everything worked perfectly. After that incident, I've pretty much come to the conclusion that Screws are NOT made for Structural Construction. None of them. Nails may bend, but still hold the boards together. But screws break, and when they break, the boards do not stay together. In fact, they're dangerous.
Unless they make a screw specifically for structural construction, (which I am not aware of), I dont recommend using screws for any structural construction at all. Stick with nails.