If you go by the default constitutional allocations, Congress starts with much tighter control of how the executive operates than it does now. Via passage of laws, Congress over the years has chosen to delegate a lot of responsibility to the executive branch - some for pragmatic management reasons, but some as a trend of historic concentration of power towards the executive. Congress can also delegate to non exec branch bodies like the Fed and other quasi-govermental orgs. Congress has the constitutional purview to take back a lot of that power into it's direct hands instead of allocating it to other bodies if it so chose.
> Via passage of laws, Congress over the years has chosen to delegate a lot of responsibility to the executive branch
Part of the reason for this is that 2-year presidents are more common, they make promises within the first two years and even if they meet them, it can take years for effects to be seen in the general population, so the party loses majority in the midterms and then nothing happens politically for the remaining two years. Congress is often slow and burdensome (for good reason) but it always makes out for a disenfranchised voter base
