Every cemetery is different. We tell our guys to break the cemetery into blocks (usually from access road to acces road.) Some are faster to trim the rows, others it is faster to start at one end of the block and trim as you go. The best way to improve time is repetition, have the guys trimming start at the same spot and do it the same way every time. This way they know which stone needs to be done next, this also help to eliminate missing stones while trimming.