If it's just a single unique asset then creating it as such would be perfectly fine. And in this case would give a lot more opportunity to create a higher quality asset at little or no extra cost.
This is also a very viable method. Before Substance came along a lot of tiling textures came from the Zbrush factory. A lot of people still prefer to do it this way. It's a case of preferring to sculpt or preferring a more tech artist approach(Substance) I say if you're interested in this stuff then create your texture…