I *believe* that the issue you are talking about happens when a texture is "stretched"  at its ends.  To take the classic example, you texture a fuselage left and right, but across the top (or bottom) where the textures meet, a colored pixel will be stretched.

For FSDS, what some people will do is to split off the top and bottom polygons as their own part, and texture accordingly.  Sometimes this is really the only way to do it, particularly when you had an almost flat upper (or lower) surface.

Yes and no.

You end up texturing a part consisting of polygons split off the original part.

In this first image, you can see how I have split the fuselage texturing.  The sides left/right are one part, the top/bottom is another part.

Note that the "IL 103"  is on the upper side of the left fusealge and curves over to the "top"  Had I left it as one part, the upper part of the letters would have had some distortion because of the upper pixels getting stretched.





I will admit that this is where I used FS Repaint.   AFter typing in the "IL 103"  I copied and pasted again to the "top" section.  There I could adjust the lettering to fit against the lower section - taking advantage of the default editor's ability to render on screen as you paint something - rotated ever so slightly to fit,



I could then decide to join all the fuselage parts together, but, havn't seen a need to.