Tell us about yourself!
Sorry. I missed the point you were making in trying to discredit the stair-making formula. However, along with this formula goes the other rule about never having the rise higher than 8". I didn't mention that in my original post as it didn't seem applicable to the article.
Yeah. I'm just going by the materials the author listed in his narrative of how he built the stairs.
Pressure treated lumber is available in nominal sizes of 4x4, 6x6, and 8x8. The creator of the Rustic Stairs says he used 8x8, which is actually around 7.5" high when used horizontally. With steps you don't ever want to go more than 8" of rise. It's too exhausting to climb more than that. He built the steps with a run of 16" so you would be almost correct using 4x4s (3.5+3.5+16=23). The problem with that in the author's case is that it would have made for twice as many steps. It is recommended that after about 10 steps you build in a landing. To have that his run would have been too long.
I think you've got it reversed. It would be almost impossible to climb a staircase with 11" high steps and treads only 4" deep. If you want a 4" rise you need a 16-18" run. If you've ever climbed the Mayan pyramid at Chichen-Itza in Mexico you would have seen and felt the problem of high rises with shallow runs. Those steps are about 11" high and about 5-6" deep. They are scary to climb. Apparently the Mayans designed them that way to prevent sudden attacks on those at the top.