From what I understand, a construction "blue book" would give work rates for common tasks. How long it takes one man to dig a trench 10 yards long, or lay a 10

From what I understand, a construction "blue book" would give work rates for common tasks. How long it takes one man to dig a trench 10 yards long, or lay a 1000 bricks. From this you could calculate how long the entire job would take. When I first encountered "Project Managers" in the 80's they were still trying to fit this model to software development.