Prior to the mid-1940's, many utility poles were made with a gable roof. This especially applies to the old, grayed utility poles. However, I've also seen some dated 1955 with a gable roof, as well as a tannish colored one like that from 1940 bearing the name "PEN CREO" on its engrave mark, with the "4" on top and the "0" on bottom, in a diamond shape. I also discovered several other such poles like this 1940 one on Route 2 in Gill.
I saw one pole, in Leyden, with a sideways gable roof. Instead of it being parallel to the road, it was perpendicular to it.
There were also some old poles made with a slant roof. This mostly applies to earlier utility poles made at the time of the old and grayed ones that are usually light brown in color, such as earlier telephone company poles that are shorter in height. I've also seen a few, but not very many, grayed cedar poles with a slant roof.
Most poles from the 1940's on have a flat roof, which is very common today. A few cedar gray poles even have a flat roof. Most of the ones I know of are Naugle ones dated 1946 and B.G. Hale ones dated 1949.