ive been looking at a new build first fix plumbing setup and it seems the plumbers have consistently brought supply pipes down from the ceiling to basins, toilets etc and in each case one or both (if relevant) supply pipes come straight down from a common rail in the ceiling, approximately 6 inches to the right or left of where they will be used, then they use an elbow to go 90 degrees and then a long radius bend into position of where the terminal fitting is before the tap.. Just wondering whether this has a purpose? It seems deliberate, given that every outlet has this arrangement