The Psychology of Management by Lillian Moller Gilbreth

3. physical development.

As for the regularity of the work--we have (a) The apportionment of the work and the rest. Under Scientific Management, work time and rest time are scientifically apportioned. This means that the man is able to come to each task with the same amount of strength, and that from his work he gains habits of regularity. (b) The laying out of the work. The standards upon which the instruction cards are based, and the method of preparing them, assure regularity. (c) The manner of performing the work. Every time that identical work is done, it is done in an identical manner. The resulting regularity has an excellent effect upon the physical welfare of the worker.