we use a 2nd guy on the roof and a rope and harness. The point is to keep the other guy from slipping. most roof anchors were never meant to be used every year, year after year, as they all have very specific instructions about using 10-18 screws. you do a home for 3 or 4 years, you are going to have to put the anchor in roughly the same spot each year. the roof will leak. period.