I usually piece my borders cause sometimes the border is whatever fabric I have enough left of. There have been a couple that I think would have looked much better if I had used a single long cut on, my recent oriental quilt being one of them but......
Maybe in the future, If I have my border planned ahead of time and have enough length and it is a larger print that really needs to not be seamed I will endeaver to make it one long piece. A lot of the time, I wait to see what my quilt says after it is together (and again, whatever fabric I have enough of)