Using UV spacing is not that accurate in 3d space. For accurate grids on surfaces, something like panelingtools needs to be used: Equal Grid Across Surfaces - #10 by scottd
And also, not all shapes (in fact very few) can be covered by planar, square panels that can be unrolled to flat without stretching. To handle doubly curves surfaces some stretch or play needs to be introduced at the joints or in the panel itself. Reduce number of panel units for mapping double-curved surface - #16 by scottd