I remember when I first started out as a helper. The first few years it was super enforced to make my wiring neat as possible. As I wired, I'd make everything horizontal and vertical and laugh to myself as the masters would run wires diagonal. I would think to myself " wow that looks worse than mine, it looks like a hack did it". I was not paying attention that alot of times they were moving boxes that I placed wrong or the contractor needed to move and the wiring was too short for 90 degree pretty bends and it was necessary to run diagonal or rerun all the wires. As the years went by, My helper views on this matter changed as my responsibilities did. Time frames, amount of wire used, home owner/contractor changes and structural details became more important. I realized that although diagonal may not be as pretty or my prefered method, sometimes it is necessary and more economical.