I believe you're talking about the checks and balances that are functions of the US Senate so I will base my answer on that.
The senate has two representatives from each state, no matter how small the state is, this is equal representation, as opposed to the proportional representation in the House of Representatives, Senators also have longer terms than other governmental positions. This is because the founders intended for the senate to be the more "grown up" part of the government, their role is to oversee the rest of the government and basically just make sure they don't do anything stupid or insane.
As such, the senate is required by the constitution to oversee a lot of important decisions made by the other branches of government. These checks and balances in the senate are designed to allow the senate to balance the power of the other branches and prevent anyone from abusing their powers or gaining too much power.
Basically, the founders were extremely paranoid about corrupt government officials and didn't believe it was enough to just separate the powers and checks and balances in the senate are the reason they're able to do things like impeaching the president for acting illegally.