Every observation you make in day-to-day life can draw useful analogies to your professional activities. Today while I was serviced by the girl at the cash register at the super store I noticed that she wanted to optimize the process of scanning product codes. She grouped units of the same products to scan their code only once and correct quantities in the register. Theoretically this should have taken less time than scanning code of each product unit. In fact, because of this “optimization” I had to stay at the register longer that it would without optimization. Grouping of the units the same products took her very long. So although the cashier made fewer operations the whole process took longer. The main lesson from this observation is that you should optimize the whole system (end to end sequence of steps) not separate steps or parts of process. Theory of constraints tells us that every process (or system) has a bottleneck and it is this bottleneck that should be addressed by optimization. So be sure to measure and keep an eye on performance of the whole system while optimizing.