"Sorting" is to rearrange values according to the magnitude relationship.

It takes much time than we think. For example, in the case of the bubble sort, we repeat looking at neighboring two items and move the task with the highest priority up. Suppose there are N items in the list, we need to compare values N ( N - 1) / 2 times. For N = 10, it is 45 times and for N = 100, it is 4950 times. If you can compare and rearrange two items in only 3 seconds, you can sort 10 items in 135 seconds, about 2 minutes. However, you need more than 4 hours to sort 100 items.

There are more efficient sorting algorithms than the bubble sorting. However, when the number of items is multiplied by 10, the time to sort increase more than 10 times. The higher the number of items, the higher the cost of prioritization.

Even if you can compare items in 3 seconds, it takes much time. In reality, many people spend more time worrying which task to give priority.