time-and-motion study 
noun
A procedure in which the efficiency of an industrial or other operation is evaluated: a recent time and motion study shows that seven additional workers are needed...
- The army group undertook a time-and-motion study of the most efficient way of laying mines.
- I say run a time-and-motion study test on them and see how they get on.
- At the same time, time-and-motion studies were undertaken to analyse and improve efficiency.