The founding fathers thought about efficiency in a government in the following way. They believed it was really important to work in a competent way, but that efficiency and order weren't as important as the liberty of people. For this reason, they included systems in the Constitution to limit the power of the government to avoid authoritarianism.
Since they believed that one of the main purposes of the Constitution was to provide and secure general welfare, as well as to create a strong and united nation that preserved individual rights (like the Bill of Rights), they decided to use two systems.
On one hand, "separation of powers". The government's power was divided into three different branches (legislative, executive and judicial).
On the other hand, they added a system of internal checks between the three powers called "Checks and Balances", to prevent and ensure that no branch could dominate over the other.
