You'll always have stretching, you'll never be able to get rid of it unless you have a seam on every edge, which is going to make the asset too hard to work on and too costly to use in games.
The question is, will the seam be in an optimal spot and is the stretching acceptable? It really depends on what you plan to put on the material?
A straight line? It will probably distort.
A rusty pattern? Probably not going to notice.
Are you going to texture the highpoly (if there is one) and bake? You can often mitigate stretching that way because it takes the stretch into account and squashes or stretches the texture in those areas, provided your high isn't stretched (procedural materials or different UV layout).
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The question is, will the seam be in an optimal spot and is the stretching acceptable? It really depends on what you plan to put on the material?
A straight line? It will probably distort.
A rusty pattern? Probably not going to notice.
Are you going to texture the highpoly (if there is one) and bake? You can often mitigate stretching that way because it takes the stretch into account and squashes or stretches the texture in those areas, provided your high isn't stretched (procedural materials or different UV layout).