Highly advanced technology and knowledge is involved in trying to find the answer for this question.
In my research on historical canvases used by Master Painters I notice that some conservators from painting departments write in their technical studies about the canvas. They mention the structure; plain weave, twill or diamond structures, (mantelillo) and sometimes I find a thread count per cm for the warp and the weft.
The specialists in technology and computer engineering , who make digital maps of canvases, are expressing thread count in warp and weft per cm, sometimes up to 2 numbers after the digital point.
I have not found yet more literature from textile conservators about painters canvases than the publication in ICCROM library about the El Greco canvas. Because of lining canvases for conservation, there is no longer access to the original textile.
As a hand weaver, making reconstructions of canvases used in master paintings I find that more aspects might be involved to answer the above question...