I always thought the canonical way to place the black keys was to divide the octave in the two parts that have the sequential black keys (C-D-E and F-G-A-B), and then simply place the black keys so they're the same distance away from each other and the edge of the parts.
That means that the white keys in each of the groups have "mirrors": for example, C is a mirror of E, D is a mirror of itself (it's the only key like that), F is a mirror of B, and G is a mirror of A.
I just looked at the keyboards I have around me (a slightly-above-low-end digital piano, a small midi controller, and a small 90s synth), and they all seem to fit that description.
ETA: note that the image in the article doesn't fit this description: for example the D is way too narrow (the black keys around it should be much further apart).
ETA2: I just noticed that this seems to be the "B/12 solution" described in the article.
That means that the white keys in each of the groups have "mirrors": for example, C is a mirror of E, D is a mirror of itself (it's the only key like that), F is a mirror of B, and G is a mirror of A.
I just looked at the keyboards I have around me (a slightly-above-low-end digital piano, a small midi controller, and a small 90s synth), and they all seem to fit that description.
ETA: note that the image in the article doesn't fit this description: for example the D is way too narrow (the black keys around it should be much further apart).
ETA2: I just noticed that this seems to be the "B/12 solution" described in the article.